Few long term studies have reported observations of changes over time with consultation-liaison (C-L) populations. This is a longitudinal observational study of a tertiary care psychiatric C-L- service over a ten-year-period (1988 - 1997) using a standardized computerized clinical database to examine 4429 consecutive referrals. Sociodemographic variables, relative consultation rates, reasons for referral, and psychiatric diagnoses, apart from a shift from adjustment disorders with depressed mood to major depressive disorders within the depressive syndrome group, did not demonstrate significant changes during the study period. Changes occurred in the pattern of C-L-psychiatric recommendations, e.g., in the prescription of antidepressants where tricyclic antidepressants were replaced by newer agents such as the selective serotonin reuptake inhibitors (SSRI), beginning with the introduction of fluoxetine to the US-american market in 1988. Due to a decrease in length of stay (LOS) over the ten year observation period the correlation of lagtime (the time from admission to the hospital until referral to C-L psychiatry) and LOS decreased from very strong to moderate.