Acute epidemic salmonellosis was investigated in the winter of 1978 in 4 dairy herds in the Waikato district. The outbreaks involved pregnant or recently- calved cows. Calves were affected on only one farm.Salmonella bovismorbificanswas isolated from the faecal, uterine and environmental samples from the herd most severely affected. In this herd 20, (20%) of the cows died; 10 calves were either born dead or died soon after birth; and 10 cows were culled as unlikely to return to production.S. typhimuriumwas involved in the outbreaks in the other 3 herds and from one of these farms salmonellae were isolated from the faeces of the 2 farm dogs and from a 12-month-old infant with dysentery. Salmonellae were recovered from all of the clinically ill cows and from 36% of the asymptomatic animals. Salmonellae were widespread on the properties and were isolated from 81% of soil samples; 36% of drain swabs; and from all the pairs of rubber boots worn while collecting samples.