Echocardiography plays an important role in diagnostic methods in cardiology, but its real contribution to ambulatory practice has still not been defined. For this reason, we have reviewed all the echocardiograms (echo) recorded during 1979 on non-hospitalized subjects at the echo laboratory of the cardiology center at the Geneva University Hospital. From a questionnaire answered by the physicians approximatively two years after the echo recording, follow-up of the patients and clinical impact of the method have been analyzed. 220 adult patients have had an M-mode echo, 70 of them have also had a two-dimensional echo. The follow-up of 141 patients has been analyzed. Contribution to diagnosis related to the clinical indication: Group I "precise cardiopathy": well defined cardiological diagnosis obtained by the physician (152 patients). The clinical diagnosis was confirmed in 25.5 p. 100 of the patients, diagnosis was quantitatively completed in 19 p. 100 of the patients, it was partially or totally unconfirmed in 53 p. 100 of the patients. Group II "cardiopathy X": cardiac lesion suspected, but clinically not identifiable (48 patients). The echo allowed a precise diagnosis in 12.5 p. 100 of the patients, but it showed non classifiable anomalies in 25 p. 100, normal recordings in 60.5 p. 100, and technical failures in 2 p. 100 of the patients. Group III "controls": precise diagnosis already know (20 patients). The echo supplied a quantitative complement in 19 patients and allowed a new diagnosis in one patient.(ABSTRACT TRUNCATED AT 250 WORDS)