Small intestinal motor activity is important for the optimal digestion and absorption of nutrients. These motor responses to feeding are frequently abnormal during critical illness, with the persistence of migrating bursts of contractions during enteral feeding. Whether this disturbance influences nutrient absorption is not known. In this study, the effects of small intestinal burst activity on lipid and glucose absorption were evaluated in ten healthy human adults (6M; 4F, 19- 47 years). Upper gastrointestinal manometry was recorded for 6 hours, during and shortly after a 20 minute intravenous (IV) infusion of (a) erythromycin (1mg/kg) to stimulate burst activity or (b) saline (0.9%), in a double blind randomized fashion. Simultaneously with the start of the IV infusion, 60ml of liquid feed mixed with 200µl ¹³C-triolein and 2g 3-O-Methylglucose (3-OMG) was infused intraduodenally for 30 minutes. Absorption of lipid and glucose was assessed using the ¹³C- triolein breath test and plasma concentrations of 3-OMG, respectively. Infusion of erythromycin was followed by a more rapid onset of burst activity following commencement of the duodenal infusion compared with saline (30 ± 6.1min vs 58 ± 10.7min; P < 0.05). Erythromycin was associated with a slower recovery of ¹³CO₂ (P<0.01). A positive correlation existed between the time to onset of burst activity and ¹³CO₂ recovery (P< 0.001). Erythromycin had no effect on 3-OMG absorption. In conclusion, stimulation of small intestinal burst activity reduces the rate of lipid absorption, but not glucose absorption, in healthy human adults.