Experience with computer-aided diagnosis of "dyspepsia" in a consecutive prospective series of 212 patients coming to surgery is described. Analysis is concentrated upon 122 patients who presented to an outpatient clinic de novo for diagnosis. During their first (outpatient) hospital contact, a firm diagnosis was made in just over half of these patients (though where made, it was usually correct). After full investigation, the diagnostic accuracy (prior to operation) was 92.6%. Using data elicited solely from the house surgeon's interview at the time of admission, the computer's overall diagnostic accuracy was 87.7%. The cost of each new computer diagnosis was around 25 new pence ($0.60). and the time taken was about 5 minutes. In a further small series designed to discriminate between organic and functional dyspepsia, the computer correctly assigned all but 1 of 23 patients with organic disease to the correct disease category. However, almost half of 33 patients with x-ray negative dyspepsia were predicted by the computer to have organic lesions. Time alone will tell whether the computer is a better early predictor of eventual organic disease than currently available radiologic methods.