Summary.In order to describe ethnic differences in the incidence of the sudden infant death syndrome (SIDS) records of all livebirths in the State of Victoria, Australia, 1985–1989, excluding those who died in the first month of life, were linked to death certificates. Cases were defined as infants dying with a diagnosis of SIDS between 1 month and 1 year of age (n= 601) from the cohort of 308052 neonatal survivors. Ethnicity was defined by the mother's country of birth. The SIDS incidence was 2.04/1000 in infants of Australian‐born mothers. The relative risk of SIDS was 0.28 (95% confidence interval (CI) 0.15,0.55) in infants whose mothers had been born in Southern Europe and 0.48 (95% CI 0.29, 0.78) in infants whose mothers had been born in Asia. SIDS in infants of Australian‐born mothers was associated with low maternal age, high parity, marital status other than married, male sex, multiple birth, low birthweight and preterm birth. After adjustment for those factors in a case‐control analysis using a logistic regression model the adjusted odds ratio for SIDS was 0.34 (95% CI 0.17, 0.69) comparing infants whose mothers were born in Southern Europe with infants of Australian‐born mothers, and 0.60 (95% CI 0.35, 1.04) for infants whose mothers were born in Asia, compared with infants of the Australian‐born. Thus there are substantial ethnic differences in SIDS which are not explained by the classic social and perinatal r