Medication knowledge is an important contributor for medication adherence which in turn improves therapeutic outcome. To assess the patient's knowledge on antidepressants and impact of pharmacist mediated counseling on their medication knowledge, patient's medication knowledge was assessed by administering medication knowledge assessment questionnaire. First assessment was considered as baseline assessment. Patients were counseled based on their knowledge on antidepressants. They were advised to attend two follow up sessions with an interval of onemonth, during which they were administered with same questionnaire to reassess their medication knowledge and impact of pharmacist mediated counseling on their medication knowledge. The average medication knowledge score at baseline, first follow up and second follow up was 4.590, 6.431 and 7.318 respectively with statistically significant difference (p<0.01). There was a mean increase of 1.886 and 2.705 from baseline to first follow up and second follow up, and a mean increase of 1.841 from first follow up to second follow up, with statistically significant difference (p<0.01). The result shows the effectiveness of medication counseling by a pharmacist. Medication counseling done by pharmacist has significant impact on patient's knowledge. Assessment of medication knowledge in patients may influence their medication adherence, though it may not necessarily result in better clinical outcome.