BACKGROUND: A study was conducted in 2000 to describe service quality problems in a large tertiary care teaching hospital and evaluate the effect of a pre-discharge program for active complaint surveillance and resolution on patient satisfaction. METHODS: The pre-post intervention study with temporal controls was conducted at a tertiary care teaching hospital in St Louis. Eighty-four percent (1,023 of 1,218) of patients admitted to a general medical unit between October 2, 2000, and December 22, 2000, were interviewed by a patient advocate to identify and address patient complaints about service quality. Patient satisfaction was measured, using a validated instrument administered by telephone interview 7-10 days after discharge. RESULTS: The advocate completed 1,233 patient interviews and received 695 complaints about service quality. Half of the complaints concerned local unit care, most frequently delays in response to patient requests. Patients also complained about food, delays in admission and discharge, and inadequate communication about procedures. Concurrently, the hospital's formal reporting system received 12 complaints. Patients satisfaction scores were unchanged during the intervention. DISCUSSION: Active surveillance using predischarge patient interviews by a patient advocate identified many local and systemwide service quality problems in a large tertiary care teaching hospital that needed to be addressed to improve the quality of patient care. However, patient satisfaction scores were unchanged.