We studied the effects of serosal patching of a 4 x 15-cm, full-thickness, jejunal defect on absorptive function and fasting and postprandial myoelectrical activity in 5 patched and 5 control animals over a 3-month period. While fat and D-xylose absorption were similar in both groups, serum albumin was significantly depressed (2.96 +/- 0.24 g/dL preop vs 2.29 +/- 0.23 g/dL postop, p less than .05) and stool moisture content was elevated following patching (54 +/- 4% vs 67 +/- 9%, p less than .05). Neither the generation of the various phases of the interdigestive myoelectrical complex (IDMEC), the development of postprandial myoelectrical activity, or colonic myoelectrical patterns were impaired in the patched animals. The normal gradients of slow wave frequency, phase III propagation velocity, and onset of the fed pattern were similar in control and patched animals. However, jejunal slow wave frequency (cpm, control vs patch: 18.6 +/- 0.6 vs 19.5 +/- 0.6, p less than .05) and IDMEC frequency (0.36 +/- 0.25 vs 0.56 +/- 0.32, p less than .05) were greater and the IDMEC period shorter (109.6 +/- 27.8 vs 88 +/- 35.7, p less than .05) in the patch animals. In vitro studies demonstrated similar absorptive function in intact mucosa and neomucosa. We conclude that the technique of serosal patching is associated with impaired absorption in vivo. While this may be related, in part, to the minor motility changes observed, other factors such as hormonal changes may also be important.