Drug dependence is still to be recognized in developing countries as a significant public health problem and literature on the magnitude of this problem is limited. The present research was planned to study the socio-demographic profile and the reasons for substance use among patients admitted at De-addiction centres in Mangalore, India. In this cross-sectional study, all the patients admitted at the De-addiction centres during the study period were interviewed. The data was analyzed and the results obtained were expressed in proportions. A total of 83 patients were included in the study, all of whom were males. A positive family history of substance use was evident in 63% of the respondents. The mean age of the study participants was 41.9 (SD±11.2) years and the mean age for starting substance use was 20.9 (SD±7.7) years. The most common substance used was alcohol (95.2%). Majority of the subjects (56.6%) cited peer pressure as a reason for initiating substance use. Our findings suggest that the initiation of substance use occurs during late teenage years and mostly due to peer pressure. Our observations point towards the vulnerability of younger age towards substance use and hence, it is proposed that the preventive health policies in this regard should be targeted specifically during teenage years.