Introduction: Drug abuse is a prevalent issue in Malaysia, and a constant struggle to eradicate even among substance abusers who have received prior rehabilitation. Drug abuse has also been known to affect the quality of life of an individual, due to the stigma it carries. This research emphasized on studying the life quality of relapsed and first-time substance abusers in rehabilitation centres including their tendency towards aggression. Methods: A cross-sectional study was conducted to evaluate the current inpatients in Cure & Care Rehabilitation Centres (CCRC) in Peninsular Malaysia. Primary data was acquired using a self-administered questionnaire consisting of socio-demographic (Part A), quality of life (Part B) and aggression related questions (Part C). 417 individuals were selected through purposive sampling from five different centres. A statistical analysis was conducted using independent t-test, single linear regression and Kruskal-Wallis using SPSS version 25.0. Results: An analysis of the data presented no significant association between quality of life and tendency of aggression among relapsed and first time substance abusers (p>0.05). Based on the analysis and the outcome, age influences the level of aggression (p=0.018) while quality of life is affected by education level (p=0.017). Marital status is a factor that affects both the level of aggression (p=0.015) and quality of life (p=0.043). Conclusion: The findings may contribute to law enforcements in reducing violent crimes committed by drug abusers and rehabilitation efforts by rehabilitation centres, by establishing demographic profiles in relation to quality of life and aggression.