OBJECTIVE: To evaluate the outcome of pregnancies in patients with complex pulmonary atresia, comparing those with and without previous radical surgical repair. DESIGN: A retrospective study of all pregnancies in women with complex pulmonary atresia registered on the Grown-up Congenital Heart Unit database between 1977 and 1994. SETTING: Referral centre for adolescents and adults with congenital heart disease. PATIENTS: Forty one pregnancies occurred in 15 patients. They were divided into two groups; group I, 26 pregnancies in nine patients before radical repair (cyanotic); group II, 15 pregnancies in seven women after radical surgical repair. RESULTS: In group I there were three terminations, 13 miscarriages, eight healthy children, and two neonatal deaths. Five children were born prematurely and all had low birthweights. In group II there were two miscarriages, 11 normal children, and two children with congenital heart disease. None was premature and all had normal birthweights. There were major complications in both groups: in group I there were two thromboembolic complications and one episode of heart failure; in group II there was one pulmonary embolism and one arrhythmic complication, five pregnancies in three patients were complicated by left ventricular failure that was persistent in one case and progressive in another, leading to death 13 months after delivery. CONCLUSIONS: Patients with complex pulmonary atresia, with or without surgical repair, who have no or mild symptoms, can have successful pregnancies. Surgical repair decreases fetal complications significantly. In both groups thrombotic disorders and heart failure must be prevented. Patients with residual systemic-pulmonary collaterals after surgical repair are particularly at risk of left ventricular failure.