Background Clinical pharmacy is key to the quality use of medicines. While there are different approaches in different countries, international perspectives may inform health service development. The Vietnamese Ministry of Health introduced a legal regulation of clinical pharmacy services in December 2012. Objective To describe the services, and to explore reported barriers and facilitators in implementing clinical pharmacy activities in Vietnamese hospitals after the introduction of Vietnamese Ministry of Health legal regulation. Setting Thirty-nine hospitals in Hanoi, Vietnam, including 22 provincial and 17 district hospitals. Method A mixed methods study was utilized. An online questionnaire was sent to the hospitals. In-depth interviews were conducted with pairs of nominated pharmacists at ten of these hospitals. The questionnaire focused on four areas: facilities, workforce, policies and clinical pharmacy activities. Main outcome measure Proportion of clinical pharmacy activities in hospitals. Themes in clinical pharmacy practice. Results 34/39 (87%) hospitals had established clinical pharmacy teams. Most activities were non-patient-specific (87%) while the preliminary patient-specific clinical pharmacy services were available in only 8/39 hospitals (21%). The most common non-patient-specific activities were providing medicines information (97%), reporting adverse drug reactions (97%), monitoring medication usage (97%). The patient specific activities varied widely between hospitals and were ad hoc. The main challenges reported were: lack of workforce and qualified clinical pharmacists. Conclusion While most hospitals had hospital-based pharmacy activities, the direct patient care was limited. Training, education and an expanded work forces are needed to improve clinical pharmacy services.