Eighty-four patients with congenital jejuno-ileal or colonic atresia treated at this hospital during the years 1961-86 were studied. There were 42 cases of jejunal atresia, seven cases of jejuno-ileal atresia, 33 cases of ileal atresia and two cases of colonic atresia. Multiple atresias occurred in 19 patients. During the first 15 years of the study the mortality rate was 56%. In the last 10 years it was 22%. Multivariate linear modelling techniques were used to determine the factors associated with a fatal outcome. In order of magnitude associations were found between death and year of treatment (P less than 0.01), the type of anastomosis performed to correct the atresis (P less than 0.05), the presence of other congenital abnormalities (P less than 0.01) and presence of a malrotation (P less than 0.02). The anastomoses associated with the highest mortality were those with a stoma. The mean length of bowel resected proximal to the anastomosis was 15 cm and the mean length resected distally 5 cm. Eleven patients had 60 cm or less of small bowel remaining after surgery and only three of these survived. The highest mortality rate can be expected in patients with other congenital abnormalities and those with a malrotation. A primary anastomosis without a stoma is recommended.