The course of 13 pregnancies in 12 women (mean age 28 [19-34] years) after renal transplantation was analysed retrospectively. The average period from renal transplantation to the beginning of pregnancy was 45 [7-144] months. All patients received methylprednisolone for immunosuppression, while seven each additionally received azathioprine and/or cyclosporin. At the onset of pregnancy the transplant function was good or only slightly impaired in 11 women (serum creatinine 1.3 [0.8-1.8] mg/dl). But in one patient, a diabetic with nephrotic syndrome, serum creatinine concentration was raised to 2.4 mg/dl. In six patients the cyclosporin dosage had to be increased during the pregnancy. Severe complications were: acute rejection in the 16th week of pregnancy; acute renal failure during a recurrence of haemolytic-uraemic syndrome in the 36th week; and severe renal anaemia (haemoglobin 6.7 g/dl). An irreversible rise in creatinine concentration occurred in five women and hypertension got worse in eight. The mean duration of pregnancy was 35.5 (32-38) weeks. The average birth weight was low (1892 g [970-2560 g]): five children were dystrophic. The dystrophy rate was the same under cyclosporin as under the conventional immunosuppressants. The findings indicate that pregnancy after renal transplantation presents a high risk for mother and child. It demands intensive joint care by obstetrician, paediatrician and nephrologist.