Understanding the psychopathologicai symptoms among drug addicts is an important step for treatment and rehabilitation of drug addiction. Consequently, the measurement of psychopathologicai symptoms requires a valid and reliable instrument to be used. This study aimed to examine the consistency and validity of the Symptoms Check List-90-Revised (SCL-90-;R) in measuring psychopathologicai symptoms. The SCL-90-R is a self-report inventory that has 90 items with nine dimensions namely, somatization. obsessive-compulsive, interpersonal-sensitivity, depression, anxiety, hostility, phobia, paranoia, and psychoticism. The sample consisted of 599 respondents from six drug rehabilitation centers. Results showed that the instrument has good reliability and validity indicating that it is suitable and can be used to measure psychopathologicai symptoms among drug addicts. The results of this study provide insight into the validity of psychopathologicai symptoms experienced by drug addicts which has to be taken into consideration in designing an effective treatment program. Programs that can increase the drug addicts' motivation to change must be specifically tailored to address the seriousness of clinical problems in drug addiction.