The ICD-10-Symptom-Rating (ISR) is a self-rating questionnaire for patients. According to its conceptualization, the instrument was developed to closely represent the syndrome structure of the ICD-10 while assessing the extent of psychological distress an individual suffers from. The results of different factor analyses testing the postulated syndrome structure as well as item and scale characteristics are reported here. Data was collected from a consecutive sample of 1 057 psychosomatic patients of the University Hospital Charite Berlin. Evaluation of the dimensional structure of the questionnaire included exploratory and confirmatory factor analyses each computed with a randomized half of the sample. Multi-Sample-Analyses with different subgroups of the sample were performed to test the stability of the factor structure. The individual factors were constituted by the postulated syndrome units of the ICD-10 involving a high and uniform distribution of accounted variance. They also proved themselves satisfactorily stable over the different subsamples. The scales showed a high degree of internal consistency with relatively small gender and age effects, while psychological disorders had a large effect on the means of the scales. Taking a perspective of test theory, the ICD-10-Symptom-Rating is in accordance with the syndrome structure of the ICD-10 and suitable for the assessment of psychological symptoms. Other aspects pertaining to the reliability and validity of the ISR remain to be proven in future research.