As part of a large-scale ongoing project exploring new pharmacy-based methods of postmarketing surveillance, we are comparing a patient-initiated monitoring system to a staff-initiated approach. Here we report data only from staff-initiated, computer-directed telephone interviews with 231 outpatients approximately 2 weeks after they had been prescribed a target drug chosen from two markedly different pharmacological classes for which adverse drug reactions (ADRs) are well-documented. Our results indicate that spontaneous patient reports of "new or unusual symptoms" obtained from a standardized staff-initiated telephone interview can be quite reliable, leading to accurate detection of known tricyclic antidepressant and antibiotic ADRs.