A comparative evaluation of eight psychometric instruments was made in 274 patients who were currently suffering or previously had suffered from low-back pain. The specificity and sensitivity values for detection of psychological disturbance were calculated and optimum cutoff scores determined for each test. The influence of current pain, social group, compensation, migrant status, and unemployment on the accuracy of each test were evaluated. The Pain Drawing, the Inappropriate Symptoms, the Inappropriate Signs, and the Illness Behavior Questionnaire were found to be least discriminating. The Modified Somatic Perception Questionnaire, the Hospital Anxiety Scale, the Hospital Depression Scale, and the Zung Depression Scale were the most accurate and least affected by the factors examined. The combination of the Modified Somatic Perception Questionnaire and the Zung Depression Scale yielded specificities and sensitivities of 91% and 84% for men and 96% and 85% for women, respectively. This combination is recommended for the assessment of psychological disturbance in patients with low-back pain.