Background: Pesticide poisoning is a major problem worldwide. The incidence of aluminium phosphide poisoning has increased over decades. Phosphine, active form, binds cytochrome oxidase, induces oxidative stress with release of free oxygen radicals, lipid peroxidation, resulting acute inflammation leads to alteration of various haematological/biochemical parameters, including total leucocyte count (TLC). Objectives: 1.To study TLC in aluminium phosphide poisoning 2.To study severity of toxicity in relation to TLC 3.To study in-hospital mortality in relation to TLC Methods: A hospital based cross sectional study with sample size of 65. In-patients with aluminium phosphide poisoning attending Medicine Department in KR Hospital, Mysuru were studied. The parameters like complete hemogram including TLC, liver/renal function tests, electrolytes, electrocardiogram were assessed and correlated. With a confidence interval of 95%, level of significance was kept at 5% Results: Of the 65 subjects, mean age was 34.11 ±11.55 years and mean TLC was 10467.5 ±2991.2 . Subjects were categorised into non-severe(29%), severe(26%) and death(45%) groups. Mean TLC in non severe(8140.7±2445.9), severe(10980.3± 2471.1) and death(11691.4 ±2780.4). A high TLC was found in 15.8% non-severe, 41.2% severe and 69% death cases. A significant positive correlation of TLC with severity of toxicity and mortality of aluminium phosphide poisoning was obtained (p<0.005). Conclusion: Total leucocyte count can be used as one of the easily available cost effective predictive variable to assess the outcome of aluminium phosphide poisoning.