Introduction: Human immunodeficiency virus (HIV) prevention among intravenous drug user (IDU) is the ultimate goal of National AIDS Control Organization (NACO). The government hospitals across India are expanding with opioid substitution therapy (OST) services. Aims and objectives: The primary aim was to find out the pattern of hopsacking behavior in a newly functional OST clinic in a government setup in India. As the prevalence of HIV infection is on rise, requirement of opening OST clinic are also emerging. Materials and methods: The datasheet has been made in accordance with guidelines, and the descriptive and analytical statistics study has been carried out in a tertiary medical college of a government setup in India. The new patients enrolled, total clients registered, active client load, and total client load have increased at the beginning and end of the study period. The data were analyzed using IBM Statistical Package for the Social Sciences (SPSS) version 20.0. Results: New clients enrolled during the study period are n = 62. From inception, total clients raised to 202. Very regular, regular, and irregular clients were n = 27, 10, and 72 changed to n = 56, 22, and 13, respectively from beginning to end of the study which is statistically not significant χ² = 0.0792, p = 0.961. Total number of client vs active clients during beginning and end of the study shows significance, χ² = 25.3311, p < 0.001. The relationship between new clients, total clients, treatment completed, clients with other outcome and active client shows significance in 2 × 5 contingency table, χ² = 99.3704, p < 0. 001.The relationship between sexually transmitted infection (STI) referral, HIV tested, and condoms dispensed has shown significance with χ² = 6.071, p < 0.048. Conclusion: Opioid substitution therapy is an effective therapeutic option to manage IV drug users. The screening with stringent criteria is essential before client selection.