Milk progesterone levels were measured on a daily basis for 44 dairy cows from calving to conception in order to use the progesterone profiles in diagnosing and treating reproductive disorders related to the oestrous cycle. Some of the profiles could be used to identify reproductive abnormalities, for example, silent heats (13,6%), irregular oestrous cycles (2,2%), ovarian cysts (6,8%), and embryo mortality (15,2%). The degree to which such problems were overcome could also be monitored. The wide variation in progesterone profiles made it difficult to predict the outcome of insemination. It was concluded that repeat breeding could be due to several reasons, only some of which could be identified from progesterone profiles.