OBJECTIVES: To compare poison severity score with incidence of intermediate syndrome, ventilation and outcome in organophosphate poisoning.   METHODS: A retrospective study was conducted in a tertiary care teaching hospital of South India. Data was collected retrospectively from medical record section from 2012 to 2013 in a suitable designed case record form. Data was analysed by using SPSS 20.0 with chi-square and one way anova. RESULTS: Total of 199 cases of organophosphate poisoning was documented out of which 135(67.8%) were males and 64(32.2%) were females. The average age in this group of patients was found to be 34.22 + 14.26.  The average pre-hospitalization period was 1.58 + 2.07 days. Among them majority of the cases were suicidal (94.5%). Patients with a poison severity score of grade 1, 5.8% had intermediate syndrome. In grade 2 only 33.3% had intermediate syndrome and the most was seen in grade 3 where 60% had intermediate syndrome. Patients with a poison severity score of grade 1 only 10.6% were on ventilation, in grade 2 only 56.7% were on ventilation and in grade 3, 93.8% were on ventilation.  Patients with a poison severity score of grade 1 had a recovery rate of 92.3%. Patients with a poison severity score of grade 2 had a recovery rate of 66.6% and patients with grade 3 had a recovery rate of 64.6%.   CONCLUSIONS: As the severity in poison severity score increases other parameters like ventilation, intermediate syndrome and mortality also increases. There is a strong correlation between the poison severity score and outcome of the patient.