[3] This designation was maintained when the New Testament manuscript list system was standardized by Swiss theologian and textual critic Johann J. Wettstein in 1751.

[5]: 340 Until the later purchase of Codex Sinaiticus, biblical scholar and textual critic Frederick H. A. Scrivener described it as the best manuscript of the Greek Bible deposited in Britain.

[6]: 51  Today, it rests along with Codex Sinaiticus in one of the showcases in the Sir John Ritblat Gallery of the British Library in London, U.K.[7][8] A full photographic reproduction of the New Testament volume (Royal MS 1 D. viii) is available on the British Library's website.

[9] The manuscript is a codex (precursor to the modern book) made from 773 vellum folios (specific name for pages in a codex) measuring 12.6 × 10.4 inches (32 × 26 cm),[10] bound in quarto format (parchment leaves placed on top of each other, folded in half vertically, and then folded in half again horizontally, to make a single block, then stitched together with others to create a book), which now comprise four volumes.

[11] Cowper's further description of the pages note they are "often discoloured at the edges", which have been damaged by age and more so through "the ignorance or carelessness of the modern binder, who has not always spared the text, especially at the upper inner margin".

[11] Scrivener noted that "[t]he vellum has fallen into holes in many places, and since the ink peels off for every age whensoever a leaf is touched a little roughly, no one is allowed to handle the manuscript except for good reasons.

[5]: 340 The only decorations in the codex are tail-pieces at the end of each book (see illustration), and it also shows a tendency to increase the size of the first letter of each sentence.

The larger letters at the beginning of the sections stand out in the margin as in codices Ephraemi and Basilensis.

[14]: 104  The letters Ν and Μ are occasionally confused, and the cluster ΓΓ (gg) is substituted with ΝΓ (ng).

[11][18] Punctuation is more frequent, usually on a level with the top of the preceding letter, while a vacant space, proportionate to the break in the sense, follows the end of a paragraph.

To all the Gospels (except Matthew, due to several pages missing at the beginning) is prefixed by a table of contents (also known as κεφάλαια).

[19] The various Euthalian Apparatus sections into which the Acts, Epistles, and Apocalypse were divided (similar to Eusebius' system for the Gospels) are not indicated in this manuscript.

Due to damage and lost folios, various passages are missing or have defects: Textual critics have had a challenging task in classifying the text of the codex, specifically when it comes to the New Testament; the exact relationship to other text-types and manuscript families is still disputed, and as such the Greek text of the codex is considered to be of mixed text-types.

These are then used to determine the original text as published; there are three main groups with names: Alexandrian, Western, and Byzantine.

The text of Acts frequently agrees with the biblical quotations made by the 4th century Christian writer Athanasius of Alexandria.

Gregory asserted in regard to the lost two leaves (John 6:50–8:52), "For by counting the lines we can prove that it was not in the book.

Cyril Lucaris was the first to suggest Alexandria as its place of origin, which has been the traditional view and is the most probable hypothesis.

[18]: 100  This popular view is based on an Arabic note on folio 1 (from the 13th or 14th century), which reads: "Bound to the Patriarchal Cell in the Fortress of Alexandria.

[34]: 10–11 A 17th-century Latin note on a flyleaf (from the binding in a royal library) states the codex was given to a patriarchate of Alexandria in 1098 (donum dedit cubicuo Patriarchali anno 814 Martyrum), although this may well be "merely an inaccurate attempt at deciphering the Arabic note by Athanasius" (possibly the patriarch Athanasius III).

[20][34]: 5 Codex Alexandrinus contains the Epistle of Athanasius on the Psalms to Marcellinus, so it cannot be considered earlier than A.D. 373 (terminus post quem).

In the Acts and Epistles we cannot find such chapter divisions, whose authorship is ascribed to Euthalius, Bishop of Sulci, come into vogue before the middle of the fifth century.

The presence of Epistle of Clement, which was once read in Churches recalls to a period when the canon of Scripture was in some particulars not quite settled.

[20] Codex Alexandrinus was written a generation after codices Sinaiticus and Vaticanus, but it may still belong to the fourth century.

[16] The codex was presented through the hands of Thomas Roe (together with minuscule 49), the English ambassador at the court of the Sultan.

[34]: 1 [6]: 50  It was saved from the fire at Ashburnham House (the Cotton library) on 23 October 1731, by the librarian, Richard Bentley.

[34]: 2 The text of the Epistles of Clement from the codex was published in 1633 by Patrick Young, the Royal Librarian.

[39] For the text in 1 Tim 3:16, the facsimile has ΘΣ ἐφανερόθη, and Woide in his prolegomenon combats the opinion of Wettstein,[4]: CDXCVIb–CIXCIXb  who maintained that ος ἐφανερόθη was the original reading, and that the stroke, which in some lights can be seen across part of the Ο, arose from the middle-stroke part of a letter Ε being visible through the vellum.

"[14]: 453–454  Tregelles however agrees with Wettstein's reading of the codex, and states "as the result of repeated examinations, we can say distinctly that Woide was wrong, and Wetstein was right.

"[2]: 156 Woide's edition contained some typesetting errors, such as in the Epistle to Ephesians – ἐκλήθηθε for ἐκλήθητε (4:1) and πραόθητος for πραότητος (4:2).

Woide, who defended the Greek manuscripts in general, and the Codex Alexandrinus in particular, from the charge of having been corrupted from the Latin,[39] discerned two hands in the New Testament.