Iivo Nei (born 31 October 1931 in Tartu) is an Estonian chess grandmaster.

[1] In 1947, at the beginning of his career, Nei took 3rd in Leningrad (Saint Petersburg) at the sixth USSR juniors championships won by Viktor Korchnoi.

In 1955, he tied for third through sixth place in Pärnu (Baltic Republics championships), an event won by Paul Keres.

Nei won the Baltic Republics championships in 1961 in Palanga, in 1962 in Tartu, in 1963 in Estonia, and in 1964 in Pärnu.

He was one of Boris Spassky's seconds (along with Efim Geller and Nikolai Krogius) for the 1972 Fischer–Spassky World Championship match.