Aim: The aim of this study was to determine the incidence of low molecular weight heparin (LMWH) induced thrombocytopenia in patients undergoing orthopedic surgery in Khartoum Teaching Hospital. Heparin induced thrombocytopenia (HIT) is a complication of heparin therapy in which the platelet count falls by 50% or more of the baseline value, or falls to below 150__ampersandsigntimes;109/L. Methodology: This is a prospective cross sectional study carried out in Khartoum Teaching Hospital, Department of Orthopedic Surgery in the period between April-July 2013. Results: Seventy three patients were included, forty nine (67.1%) were males and 24 (32.9%) were females. Most of the patients were between 40-59 years of age (50.7%). Sixty nine (94.52%) of the patients were not exposed to heparin before. All patients received LMWH as prophylaxis except 2 patients who received it for treatment. Fifty patients (68.49%) received LMWH in a dose of 3500 (IU) per day while 23 patients (31.51%) received it in a dose of 4500 IU. Fifty six of the patients received LMWH for 2 weeks, 15 patients for less than 2 weeks while 2 patients for more than 2 weeks. All patients had a baseline platelet count equal or more than 150__ampersandsigntimes;109/L. On day 14, none of the patients had 50% reduction or more in the platelet count from the baseline or a platelet count of less than 150__ampersandsigntimes;109/L. Conclusion: The study found that no patient treated with LMWH had significant HIT.