Jan Hajer (The Hague, 31 March 1942 - Breda, 27 August 2002) was a Dutch tennis player.

Later Hajer and Okker represented the Netherlands in the Davis Cup team.

Hajer played 18 singles matches in seven Davis Cup ties, scoring 5 victories and 13 losses.

[4] Hajer and Okker competed in doubles events in South Africa, Philippines and Australia.

This biographical article relating to Dutch tennis is a stub.