He won several tournament titles at Sochi and in Eastern European events, and appeared in seven Soviet finals from 1958–71.

Nikolai V. Krogius scored 4.5/15 for a tied 13th–14th place at Leningrad 1946 in the Soviet Junior Championship; the winner was Tigran Petrosian.

Krogius made his first creditable result in Master company at Leningrad 1949, tallying 8/17 for a tied 12th–15th in a very good field; this was a Soviet Championship semi-final, and he did not advance to the final.

He competed in three Russian Championships: at Yaroslavl 1951, in his home town of Saratov in 1953, and at Rostov-on-Don in 1954, but complete results of these events are also unavailable.

In the Soviet semi-final at Tbilisi 1956, he scored 11/19 for seventh place, and missed advancing to the final by half a point.

He made his first appearances for the USSR in team matches against Bulgaria (Sofia 1957) and Yugoslavia (Zagreb 1958), scoring 50 percent in both.

A sure sign of favour in high circles was his first trip to Western Europe for an individual tournament, Le Havre 1966, which celebrated the 900th anniversary of the voyage which led to the Norman Conquest of England.

He made one of his top career results with a shared 1st–5th place at Sochi 1967 on 10/15; the other co-winners were Boris Spassky, Alexander Zaitsev, Leonid Shamkovich, and Vladimir Simagin.

At Sarajevo 1967, Krogius scored 9.5/15 for a shared 3rd–4th place; the winners were Anatoly Lein and Dragoljub Ciric.

For the 1972 World Championship in Reykjavik, Krogius was again selected to assist Spassky prepare for what is referred to as the Match of the Century[1] against Bobby Fischer.

He tied for the title at the World Senior Championship at Bad Wildbad 1993, with 8.5/11, along with Lein, Taimanov, Bukhuti Gurgenidze, and Boris Arkhangelsky.

[5][3] Krogius was somewhat of a late bloomer by Soviet standards, although this was not that uncommon for players who lived through the Second World War during their formative chess years; other examples are Efim Geller and Semyon Furman, both of whom eventually became formidable players by their late 20s.

However, when he did get opportunities at high level, he usually made the most of them, and scored several notable tournament victories in high-standard events during his peak years in the 1960s.

In his role as coach, he was undoubtedly an important part of Boris Spassky's team for the world title matches of 1969 and 1972, and maintained a successful tournament program himself during this period.

By his mid-40s, Krogius appeared less frequently in major events, and moved on to writing and chess administration, also with notable success.