Administered the Eysenck Personality Questionnaire (EPQ) to 3 groups of male, Saudi, drug addicts enrolled in a hospital treatment program. The 50-patient groups included volunteer inpatients (VIPs), volunteer outpatients (VOPs) and involuntary inpatients (IIPs). The IIP group scored significantly higher than the VIP and VOP groups on the Psychoticism scale, the Neuroticism scale, and the Lie scale. On the Extraversion scale, the IIPs scored significantly higher than the VOPs. The only significant difference between VIPs and VOPs was on the Neuroticism scale in favor of the former. Addicts were also compared with the normative Saudi population and scored significantly higher than university students on the Psychoticism, Neuroticism and Lie scales and higher than secondary students on the Neuroticism and Lie scales. Only the Extraversion and the Lie scales correlated positively. The other scales showed independence.