Isao Koizumi (小泉 勲, Koizumi Isao, born July 2, 1945) is a Japanese former volleyball player who competed in the 1968 Summer Olympics.

In 1968 he was part of the Japanese team which won the silver medal in the Olympic tournament.

He played all nine matches.

This article about a Japanese Olympic medalist is a stub.

You can help Wikipedia by expanding it.This biographical article relating to volleyball in Japan is a stub.