Introduction: One of the most common post­operative complaints after spinal anaesthesia is post­operative urinary retention (POUR). The prophylactic effect of tamsulosin in reducing POUR in post spinal anaesthesia has not been investigated in a large scale; therefore the present pilot study was conducted to investigate the efficacy of tamsulosin compared with placebo in preventing POUR before undertaking larger study. Material and Methods: After obtaining the approval from ethical justification committee of Indira Gandhi Medical College and associated hospitals, Shimla 50 patients of ASA I and ASA II aged 20­60 years of either sex posted for lower limb /lower abdominal surgery under spinal anaesthesia were included in the study. Patients were randomised into two groups of single dose of 0.4 mg Tamsulosin and placebo. Conclusion: It was found that single dose of Tamsulosin decreases the incidence of POUR in patients post spinal anaesthesia.