In order to evaluate the extent and quality of consultation-liaison (C-L) activity in Italy, a multicenter investigation was conducted in 17 general hospitals. All of the hospitalized patients referred to C-L psychiatry during a 1-year period were assessed by means of a specific instrument (Patient Registration Form, PRF-SF). Of 518,212 patients, 4182 were referred to C-L services (referral rate = 0.72%). Typical consultations were for female patients (60.1%), admitted to medical wards (71.5%), aged 55-75 years. Most interventions were carried out within 2 days; a minority (22%) were urgent requests. Gastrointestinal and cardiovascular disorders, and unexplained medical symptoms were the most frequent ICD-9 somatic diagnoses at admission. One-third of the patients were not informed of having been referred to C-L and half of them had a lifetime history of psychiatric disturbances. Most frequent ICD-10 psychiatric diagnoses were neurotic, stress-related, and somatoform syndromes (33.1%), affective syndromes (19.4%), and organic mental syndromes (10.7%). Two-thirds of the patients were given only one consultation whereas the reminder received two to four follow-up visits. The rate of transfer to psychiatric wards was low (2.1%). Psychopharmacological treatment was suggested in 65% of cases, and 75.5% of the patients were referred to community psychiatric care at discharge. The implications of the findings are discussed.