Objectives: Admissions to the intensive care unit (ICU) related to abuse of alcohol and illicit drugs have been shown to be both common and costly. The current study aimed at evaluation of clinical characteristics of drug abuse and utility of APACHE II score and Sequential Organ Failure Assessment (SOFA) score as predictors of severity and outcome. Method: crosssectional hospital-based observational study carried out on drug abuse related ICU admissions, in the period from first of July 2018 till December 31st, 2018 were enrolled in this study. Clinical data and laboratory variables were assessed on day1, day 2, day4, day 6 and endpoint. Clinical data were employed in the calculation of APACHE II and SOFA scores. Results: A total of 87 substance abuse related ICU admissions were enrolled. Cases were subdivided into group I (tramadol or/and opioids), group II (cannabis or synthetic cannabinoids) and group III (ethanol ingestion complicated by methanol toxicity) representing 67.87%, 18.39% and 13.79% respectively. Drugs affecting CNS were co-ingested in 34.48 %. Clinical findings showed statistically significant difference in relation to type of abused substance. Both APACHE II and SOFA scores differ significantly in the three groups. Short ICU stay was noted in the majority of cases (77%). Overall, in-hospital mortality and morbidity were 11.49% and 10.34% respectively. Morbidity was higher among longer ICU stay while mortality was recorded mostly during the first 24 hours. Conclusion: APACHE II and SOFA scores can be used to determine severity in ICU patients with substance abuse, and SOFA score can point to the organ failure development.