Marianne Muis (born 28 July 1968 in Amsterdam) is a female former medley and freestyle swimmer from the Netherlands.

Swimming career

Muis competed in three consecutive Summer Olympics for her native country, starting in 1988. There she won the silver medal with the Dutch women's 4×100 m freestyle relay team, behind East Germany. Her twin sister and three-time Olympian Mildred was on the same silver winning team. Despite being of Dutch nationality she won the 200 metres medley title in 1988 at the ASA National British Championships.