ABSTRACT Drug information service provides accurate, relevant and unbiased information on drugs and any aspects related to drugs. The objective of this study was to conduct the quality assurance of drug information service provided. The study was conducted for a period of six months in the drug information centre of a tertiary care hospital in Calicut. Quality assurance was done on the basis of modified systematic approach. A total of 45 drug information queries were received in the drug information center during the study period. Among the queries majority were from pharmacy (77.78%) and nursing station (22.22%). A checklist on basis of modified systematic approach was used to verify the quality. In the queries collected 85% enquirer’s details was relevant enough and 15% were incomplete. Drug information response had a professional style in 70% and whereas 30% were not having standard presentation such as alignment or spacing, etc. Among the 20 of the drug information collected for evaluation 90% had relevant information for the query and remaining 10% needed more details. In the source of references given in the response 60% were partial and 40% were incomplete. Based on the time taken for response 55% was timely given and 45% took more time than it really required. The documentation procedure was complete and perfect in all case. Study concluded that although drug information service is actively performed the quality of service has to be upgraded. Standard operating procedure has to be framed and revised as per the lacunas found. Keywords: Quality Assurance, Drug Information Service.