According to the Afghanistan Ministry of Health, 3.5 million people use drugs, 2.4 million of which are regular users. In this cross-sectional study, it was aimed to determine epidemiological characteristics of addicts in a treatment center in Kabul. Eight hundred people were included. Statistical analysis was done with SPSS 22.0. The average age was 30.74 years, 88.9% were male, and 50.6% were married. Further, 35.9% have never been trained, 60.5% of participants were living in urban areas, 62.8% were refugees, 17.5% were unemployed, and 30.3% of them had monthly income below 147.1 USD. The average age of starting substance use was 19.9 years. "Friendship environment" was the leading reason to start (36.6%), followed by "reduce troubles" with 22.3%. The most preferred substance was cannabis (46.0%), followed by opium (25.3%) and heroin (17.0%). Heroin was the most commonly used substance lifelong (87.1%), followed by cannabis (66.3%) and opium (65.5%). When compared to individuals younger than 18, heroin use rates were 3.52 times higher in the 18-to-30 age range, 5.49 times higher in the 31-to-45 age range, and 1.86 times higher in urban residents than rural. Cannabis use was 12.24 times more among men than women, 2.79 times higher among divorced or widowed individuals than singles, 1.68 times higher among refugees than non-refugees, and 2.26 times higher among drug traffickers than non-traffickers. Opium use was 1.63 times higher for refugees than non-refugees and 3.24 times higher in those who worked in drug fields than those who did not. Periodic assessment of prevalence of drug use and the establishment of drug use monitoring systems are recommended.