To evaluation of impact of substance abuse on oral hygiene practices by an epidemiological survey at the de addiction centres. Methods: A survey was systematically scheduled to spread over a period of 6 months from November 2017 to April 2018. A total of all 350 available substance abusers attending many de-addiction centers (four) aged 18-64 years of Patna district constituted the study population. Exclusively designed questionnaire was prepared to assess the oral hygiene practices followed by the abusers in the de addiction centre. Results: Overall 53.7% uses tooth brush and 29.4% of the study subjects did not used any cleaning aids. 59.1% subjects used tooth paste but 22.9% did not use any type of material for maintaining the oral hygiene. 59.2% subjects brushed their teeth once a day but 29.4% of the study subjects did not brushed their teeth at all. Conclusion: The deteriorated oral health status among the substance abusers could be highly contributed by the poor oral hygiene practices followed by the abusers.