Objective:Clinical pharmacy services are improving in hospitals. For assessing the impact of these services, first it is important to exactly describe them by categorizing into types, severity, resolution, and accuracy. The objective of this study is to provide a detailed analysis of the clinical pharmacists’ services performed on in-patients in a teaching hospital during 28 months. Setting: Masih Daneshvari hospital, Tehran, Iran.Methods:This is a descriptive study. The authors retrospectively reviewed the notes of all services and entered them in a designed SPSS sheet. Documentation was carried out based on the “findings, assessment, resolution, and monitoring” method. The data were descriptively analyzed. Main outcome measure: Types, subtypes, severities, resolutions, and accuracies of services were defined, documented, and analyzed.Findings:In total 3152 records (2227 interventions and 925 visits with no intervention) were classified and analyzed in this study. Among all types of interventions, “improper medication use” (36.2%) was the most frequent intervention and among categories (subgroups) of “improper medication use,” “untreated indication” was the most frequent (23.7%). From the aspect of severity, 75.4% of interventions were estimated as of minor potential inconvenience to the patient (severity degree 1). Most interventions (78%) were finally recommended to the prescriber and 97.6% of interventions were considered accurate on further evaluation.Conclusion:Clinical pharmacists’ interventions are highly demanded in the hospitals. Based on the results of this study, conditions needing medication to prevent later complications in the course of therapy are sometimes ignored, which emphasizes the positive role of the clinical pharmacists’ involvements in clinical teams to improve outcome.