The fertility of dairy cattle was studied on thirty-three government farms in Kenya for five years. Most parameters of fertility showed marked differences between the various farms. Some farms showed considerable annual variations, whereas others continued to have good results during all these years and other farms only obtained results far below average. Dairy cattle fertility was fairly satisfactory with an average conception rate of 51 per cent after first inseminations and averaging two inseminations for each conception. However, the disappointing average calving-interval of 413 days was primarily due to the long parturition-to-first-insemination interval of ninety-three days on an average, and on average of 123 days in 1975. The frequency of normal heat- en service intervals (17-25 days) was too low by approximately 50 per cent, which was caused by the inefficiency of oestrus detection.