To assess the oral health and related practices of a group of illicit drug users in Delhi, India; to compare with that of non-drug users; and to assess the impact of illicit drug use on oral health. Cross-sectional study. Comparison was made with non-drug users to investigate any differences in oral health between illicit drug users and general population. Illicit drug users attending a drug dependence treatment clinic in Delhi (n=126). Equal number of non-drug users attending other outpatient departments in the same setting. Oral health practices assessed using structured questionnaire; dental caries, periodontal status and oral mucosa assessed using World Health Organization 2004 criteria; oral hygiene assessed using OHI-S. Mean DMFT and OHI-S scores amongst the drug users were 3.48 and 3.80, respectively. Bleeding, shallow pockets and deep pockets were found as the highest CPI finding in 42%, 44% and 12% of drug users respectively. Premalignant states of leukoplakia and OSMF were diagnosed in 13% and 4% of drug users respectively. Significant differences were found between drug users and non-drug users with respect to oral hygiene practices; DMFT, OHI-S, CPI scores; and leukoplakia. In multivariate analysis, illicit drug use was significantly associated with CPI highest score (OR = 2.21, 95% CI 1.08-4.52). The illicit drug users had significantly poorer oral hygiene practices, oral hygiene and periodontal health; higher caries experience; and higher prevalence of leukoplakia as compared to non-drug users. The findings of the study suggest that illicit drug use is independently associated with poor periodontal health.