Background: Acute limb ischemia (ALI) is an abrupt, life-threatening reduction in limb perfusion, prothrombotic effect makes early immune-mediated heparin-induced thrombocytopenia (HIT) identification crucial. Objective: To evaluate 4 Ts score of HIT; if it could serve as predictive value in acute lower limb ischemia patient. Patients and Methods: This prospective observational study included 54 patients with ALI, admitted to Emergency Hospital Mansoura University, who were divided into two groups according to platelet count after heparin therapy: Group I (n=31): normal platelet count after heparin therapy. Group II (n=23): Patients who developed thrombocytopenia after heparin therapy (platelet count <150 - 100× 10⁹/L). Pretest scoring system for HIT: the 4 T's was done to all participants. Results: Patients with thrombocytopenia had highly statistically significantly lower levels of platelet count, hemoglobin and hematocrit % when compared to patients with normal platelet count (at fifth day) after heparin therapy. There was highly statistically significantly of 4 Ts score among both studied groups thus, it was higher in thrombocytopenia group. Group II after heparin therapy: all cases complained of thrombocytopenia, bleeding in 8 (34.8%) and thrombosis in 8 (34.8%). Sensitivity, specificity, positive predictive value, and negative predictive value for heparin-induced thrombocytopenia as a predictor of outcome in patients with acute lower limb ischemia were 93.5%, 87.1%, 91.2%, and 92.3%, respectively, with an accuracy of 91.5% for this group of patients. Conclusion: One easy, accurate, and inexpensive way to identify patients at varied risk of HIT is to apply a clinical model to evaluate the pretest probability of HIT.