Examined personality patterns that characterize alcohol and heroin abusers in the Riyadh region of Saudi Arabi320 male inpatients (250 heroin users and 70 alcohol users) were compared with 70 medical controls (inpatients) and 70 normal controls (undergraduates). Ss completed Arabic versions of the Eysenck Personality Questionnaire (EPQ) and the Taylor Manifest Anxiety Scale. Alcohol abusers obtained significantly higher scores than other Ss in the psychoticism, neuroticism, and anxiety scales. Scores of heroin abusers did not indicate differences from controls on these scales. On the lie scale, the substance-abusing group as a whole recorded significantly higher scores than controls. The mean anxiety scores of heroin abusers and medical controls were greater than that of normal controls, but the difference was not statistically significant.