OBJECTIVES: To assess the impact of treatment guidelines on utilization pattern of Low Molecular Weight Heparins (LMWHs) in hospitalised patients at a South Indian tertiary care teaching hospital METHODS: The study was a retrospective and prospective interventional study, carried out at a South Indian tertiary care teaching hospital. LMWH use in Surgery, Medicine and Orthopaedic cases was assessed pre and post introduction of therapeutic guidelines developed by consensus method. RESULTS: About 303 case records of in-patients receiving LMWH were reviewed. Use of LMWHs was found inappropriate in parameters such as indication (10.3%), dose (31%) and frequency (14.5%) and duration of administration (31.4%). A consensus panel was constituted to develop the institutional therapeutic guidelines for the use of LMWH. Post implementation of the therapeutic guidelines suggest a statistically significant (p < 0.01) improvement in the appropriateness of LMWH use in indications (93.4%), dose (65.8%), frequency (93.5%) and duration of therapy (76.3%).  CONCLUSIONS: The study findings suggest post implementation of institutional therapeutic guidelines has significantly improved the appropriateness with LMWHs usage in in-patients.