The women's 4×100 metre medley relay event at the 1964 Olympic Games took place on 16 October (qualification) and 18 October (final). This swimming event uses medley swimming as a relay. Because an Olympic size swimming pool is 50 metres long, each of the four swimmers completed two lengths of the pool, each using a different stroke. The first on each team used the backstroke, the second used the breaststroke, the third used the butterfly stroke, and the final swimmer used freestyle (restricted to not allow any of the first three strokes to be used, though nearly all swimmers use front crawl regardless).