Drug addiction is becoming Challenging/dangerous/critical habit for physical as well as mental health. Drugs contain such kind of ingredients & chemicals which is responsible for changes in the functions of the brain and it can be raised abnormal behaviours i.e., depression, stress, etc. because of these things this topic is very important to study. The objective of the present study was compared to depression, stress, and happiness among drug addicts and non-drug addicts. In the study, 30 drug addicts, those were admitted in a rehabilitation Centre located in Chandigarh (India) and 30 nondrugs addicts’ people who were not using any kind of drug were included. Depression, stress, and happiness were assessed by psychological tests, i.e., the beck depression inventory, perceived stress scale, and the Oxford happiness inventory. To find out the results descriptive statistics, t-test was used, the results showed that drug addicts significantly differ from non-drug addicts on the basis of the above-mentioned variable. In the end of the study, it can be concluded that drug addicts should have to take healthy ways to cope up with their psychological issues.