Substance Use Disorder is a frequent problem in Bangladesh and many of these patients develop psychosis. Substance use can cause psychosis and it can modify the course of psychosis. This cross-sectional study was done to see the proportion of substance use in patients with First-Episode Psychosis (FEP) in two tertiary care hospitals in Dhaka, Bangladesh mentioned here as Bangabandhu Sheikh Mujib Medical University and Dhaka Medical College Hospital; from November 2007 March 2009. Fifty consecutive FEP patients were taken as subjects and 50 healthy attendants were recruited as control. Mean age of the patients was 27.24, male (62%) are more having first-episode psychosis than female (38%). Majority of the patients were unmarried (64%). Regarding occupation students were 34%, followed by unemployed 24% and service18%. In control group's occupation; service 34%, housewife 22%. Life time substance use was found double in patients with first-episode psychosis than control. Cannabis was found to be the most common substance causing psychosis. Among the lifetime substance users in fist-episode psychosis patients 77.78% were male where as, in control group 100% patients were male. However, the researcher did not find any of the first-episode psychosis patients taking current use of substance (abuse and /or dependence). The small size of the present study was only 50. Future prospective study is required having large sample size to see the outcome of substance use in first-episode psychosis.