Automated methods of peritoneal dialysis have developed as alternative methods of treatment to CAPD. We review our experience of 47 patients treated with nocturnal intermittent peritoneal dialysis (NIPD). Patients receive a nocturnal exchange of 15-25 litres of dialysate with the peritoneum left dry during the day. If biochemical control is inadequate, 1 litre of dialysate is left in during the day. Indications for NIPD included social reasons and CAPD failure due to poor ultrafiltration or problems related to raised intra-abdominal pressure. Some features of biochemical control were less good with NIPD compared with CAPD with higher phosphate (2.18 mmol/l versus 1.83 mmol/l, P < 0.001); creatinine (1256 mumol/l versus 1085 mumol/l, P < 0.001); and potassium (4.92 mmol/l versus 4.64 mmol/l, P = 0.056) in patients changing between CAPD and NIPD. Overall peritonitis rate on NIPD was one episode per 47.1 months compared with a rate of one episode per 17.5 months for patients commencing CAPD over the same period. Conversion from CAPD to NIPD was successful in all six cases for problems related to raised intra-abdominal pressure on CAPD and in six of nine patients transferred due to poor ultrafiltration. NIPD is a useful form of treatment and we believe that the increased cost is offset by the reduced peritonitis rate.