Myrina (Greek: Μύρινα) (Also known as Kastro) is a former municipality on the island of Lemnos, North Aegean, Greece.

In addition to the town of Myrina, the municipal unit includes the communities of Káspakas, Platý, Thános, and Kornós.

Strong winds are a feature of the island, especially in August and in winter time, hence its nickname "the wind-ridden one" (in Greek, Ανεμόεσσα).

[8] Modern day Myrina is built upon a shallow bay split into two by a promontory jutting out to sea and carrying the ruins of a Venetian castle.

In 2001 the town had 3,022 regular dwellings, of which 30.4% were stone-built, and 75.6% had pitched roofs made of red tiles (source: 18.3.2001 Census, National Statistical Service of Greece).

Behind the fronts of the two Shores, the town is divided into 4 parts: the old town core (encompassing the aforementioned Shores), referred to as Kastro (after the Castle atop the promontory); Androni, to the north (where the women of prehistoric Lemnos are said to have drugged their men before tossing them from the cliff of Petasos (the north horn of the bay of Myrina)); Tchas (most probably from the Russian word часовой, which means sentinel, sentry, or guard, because there was a Russian garrison stationed there for a short time at the end of the 18th century; less probably from the Russian word час, which means hour), just behind the harbour area; and Nea Madetos, a new (post-1980) settlement of workers´and fishermen's houses on the hill overlooking the Turkish shore from the south.

Myrina also boasts a good provincial hospital, in the Tchas quarter, while presently is in the process of modernising its sewage system.