The process of parturition, including the preparatory changes, was investigated in 159 animals during their first and subsequent calvings. Altogether 493 parturitions were studied in the following breed-groups of Swedish dairy cattle: Swedish Friesian (SLB), Swedish Red and White (SRB), first generation SRB × SLB crosses bred to either SRB or SLB sires, and Swedish Jersey (SJB). A wide variation between cows was found regarding both onset and progression of the external signs of impendent calving. The time for preparation of calving — swelling of the vulva and relaxation of the pelvic ligaments — increased significantly (0.001 ≤ P ≤ 0.05) with increasing parity, i.e. pluriparous cows showed signs of impendent calving earlier than primiparas. As regards enlargement of the udder, an inverse pattern was seen. The repeatabilities between parities for time intervals of signs of preparation were generally low (0.06-0.17). No difference was found between breeds regarding preparation for calving. An analysis of the value of various signs of impendent calving for predicting that calving would take place within 12 h after external inspection revealed that relaxation of the pelvic ligaments and udder distension were the most reliable and useful signs. For the events entrained during parturition (from the onset of restlessness until calving was completed) a significant effect of breed was found. The calving process proceeded faster for Jersey than for the other breeds. In the group of crossbred dams, the breed of the calf's sire affected the course of parturition. The process took longer for SLB-sired calves, being more similar to that of purebred SLB, whereas calving was quicker for the SRB-sired calves and was more similar to that of purebred SRB. The repeatabilities within dam for the later phases of the parturition process were higher (0.18-0.45) than for the preparatory signs. For stillborn calves the time interval from onset of labour until calving was completed was approximately twice as long as for liveborn calves. Rearing intensity, season of calving and sex of calf did not significantly affect any of the signs of preparation for calving or the signs during the process of parturition.