To study the attitudes and knowledge of pharmacists in Hong Kong toward the reporting of adverse drug reactions (ADRs).In December 1993, all pharmacists who were working in retail shops (n = 230), hospitals (n = 44), or outpatient clinics (n = 12) in Hong Kong were sent a questionnaire as well as a letter explaining the purpose of the survey.One hundred and twenty-nine pharmacists (retail pharmacies 40.4 percent, hospitals 68.2 percent, outpatient clinics 50 percent) responded. Although 93 percent of the pharmacists in this survey agreed that it is necessary to report ADRs, a much smaller proportion (14.7 percent) had actually done so in the previous 12 months. Most pharmacists (87.4 percent) were not aware of any ADR reporting system in Hong Kong. There did not appear to be a relationship between ADR reporting and the length or place of practice, workload, or patient contact time. Severe or unusual ADRs and ADRs to new products were perceived to be significant enough to report.The great majority of pharmacists in Hong Kong agreed on the necessity of reporting ADRs. The lack of knowledge of an ADR reporting program might have led to nonreporting in the past. It is important that there be continuing efforts to promote ADR reporting programs.