During recent years there has been increasing evidence for extraoesophageal dysfunction in achalasia. The aim was to investigate whether motility of the small intestine is abnormal in achalasia. Thirteen patients (eight men, five women) aged 52 (33-85) years were studied. They had all previously undergone treatment with pneumatic balloon dilatation and were free of dysphagia when examined. Ambulatory 24-h motility was recorded in the upper jejunum under standardized caloric intake with a digital datalogger and catheter-mounted pressure transducers located beyond the ligament of Treitz. Visual analysis was performed by two observers and data underwent quantitative analysis of phasic contractile events using a computer program. Normal values were obtained from 50 healthy controls. In the fasting state, a complete loss of cyclic MMC activity (n = 2), an abnormally prolonged phase II (n = 2) and disturbances in the aboral migration of phase III (n = 5) were observed. Postprandial motor response was absent (n = 2) or frequently showed a contraction frequency below the normal range (n = 5). Further abnormalities consisted in hypomotility during phase II (n = 3) and in a reduced frequency of migrating clustered contractions in the fasting (n = 2) or postprandial state (n = 2). In addition, motor events not present in any healthy subject, giant migrating contractions (n = 5), retrograde clustered contractions (n = 6) and repetitive retrograde contractions (n = 3) were identified. Each patient exhibited findings out of the range of normal. Dysmotility of the proximal small intestine is present in achalasia.