OBJECTIVE To evaluate the efficacy of a training technique to improve clinical interview skills connected with Primary Care doctors' psycho-diagnostic ability: visual contact, posture, verbal and non-verbal ways of advancing the interview, verbal interruptions and questions with a psychological content. METHODS The doctors were randomly divided into two groups. A before-and-after design with blind evaluations was used. METHODS University postgraduate Internal Medicine Course. METHODS 20 doctors. METHODS Step-by-step training with feedback, using role-play and video-recording (experimental) was compared with a self-administered teaching programme (self-training). RESULTS Skills were measured by video-recordings of a patient interview one month before and one month after the intervention. The Observation Scale of Doctor's Skills was used. In the second evaluation, the experimental group differed from the self-training group in visual contact, posture and non-verbal ways of advancing the interview. CONCLUSIONS The efficacy of a training technique in improving non-verbal active listening skills was shown. It was valuable as a support to the psycho-diagnostic ability of the doctor.