Although congenital malformations are believed to be on the rise in the oil production areas of Nigeria, few baseline data are available. This retrospective study documented the incidence of congenital abnormalities in 2 major hospitals in Port Harcourt, an oil-rich city in Rivers state, Nigeria. Delivery and nursery records were reviewed from January 1990 to December 2003. In the first hospital 78 congenital anomalies were recorded out of 19 572 births (4.00/1000), principally affecting the central nervous system (1.84/1000) and skeletal system (1.74/1000). In the second hospital, 47 congenital anomalies were recorded out of 20121 births (2.20/1000), with malformations of the central nervous system (0.80/1000) and skeletal system (1.14/1000) again predominating. More research is needed into long-term trends in congenital malformations and possible associations with environmental pollution in Rivers state.