OBJECTIVE: To describe the epidemiological characteristics of oral clefts occurring with other birth defects in Victoria, Australia. METHODS: Information on infants and fetuses reported to the Victorian Birth Defects Register from 1983 to 2000 was collected. Birth defects were classified as Pierre Robin Sequence, chromosomal anomaly, nonchromosomal syndrome, single-system defect, or multiple-system defect. Pregnancy outcome and associations with selected infant and maternal features was examined. RESULTS: One third of the 2022 oral clefts recorded had other birth defects. There were more overall cleft cases involving multiple systems and chromosomal anomalies than any other birth defect group. The prevalence ratio of cleft lip with or without cleft palate (CL/P) was highest among multiple-system defects and chromosomal anomalies. Perinatal mortality was high, with termination of pregnancy highest in CL/P and chromosomal anomalies and multiple-system defects. There was a nonsignificant excess of clefts among multiple births. Women >or=40 years old had a tendency toward having a child with a cleft palate and another birth defect. There was an increased likelihood that women born in the U.K. would have a baby with CL/P and another birth defect. CONCLUSIONS: This is among the first reports in Victoria, Australia, describing oral clefts and other birth defects and associations between infant and maternal factors. Although some findings confirmed other population-based studies, some continued to be at variance. Nonetheless, the data derived support examination of babies diagnosed with clefts for associated comorbidities.