&NA;5‐Aminosalicylic acid and its metabolite, N‐ac‐5‐ASA, were measured in the plasma, urine, and ileostomy effluent of 24 ileostomates who ingested 750 mg Rowasa I®following an overnight fast. Twelve subjects previously had a small‐bowel resection or had part of their small bowel out of circuit (mean 95 cm) (Group I) while 12 had an intact small bowel (Group II). The mean peak plasma concentration of N‐ac‐5‐ASA was 1.11&mgr;g/ml in Group 1 subjects compared with 2.80&mgr;g/ml in Group II subjects(P=N.S.). On average, 53.0 percent of the ingested Rowasa I was detected in the 24‐hr ileostomy effluent of Group I subjects compared with 45.3 percent in the Group II subjects(P=N.S.). The mean recovery of 5‐ASA and N‐ac‐5‐ASA in urine was 8.5 percent in Group I and 35.6 percent in Group II subjects(P<0.001). These studies demonstrate that 5‐ASA is released and present in the small bowel following oral ingestion of Rowasa I in patients who have or have not had small bowel resections.