Forty patients with clinically and electromyographically proven carpal tunnel syndrome were examined for the frequency of concomitantly occurring Raynaud's phenomenon. The angiologic work-up was based on a detailed vascular history and examination, Doppler sonography to determine systolic digital artery pressures before and after exposure to the cold (10 degrees C for one minute), and thermoplate tests for recording heat convection of the hands at normal room temperature and measuring rewarming time after standardized cold exposure. Only 10% of the patients were found to have manifest Raynaud's phenomenon. The incidence was thus the same as in the general population. In addition, Raynaud's phenomenon and the carpal tunnel syndrome were poorly correlated with respect to their preliminary symptom appearances. Consequently, the carpal tunnel syndrome can no longer be regarded as a disease underlying Raynaud's phenomenon.