The purpose of this study was to apply the change in forearm transcutaneous partial pressure of oxygen (tcPO during a cold provocation test (5°C, for to min) to the diagnosis of vibration syndrome. The finger skin temperature of the referentsdescended rapidly soon after the start of the test and rose slightly after 5 min. In the workers with vibration-induced white finger (VWF), the finger skin temperature did not rise during the test. These results suggest that the cold vasodilatation reflex of the finger is absent in workers with VWF. The forearm tcPO of the referents increased gradually during the first 3 min of the test and decreasedthereafter. It returned to the pretest level in 5 min. In the workers with VWF, the forearm tcPO also increased during the first 3 min of the test, but it did not changethereafter. The level of tcPO increases with the increase in skin blood flow. Therefore, it might be supposedthat the forearm tcPOz changesin the workers with VWFwerecaused by the continuous relative increase of blood flow in the forearm skin, the blood flow increase having been induced by the lack of a cold vasodilatation reflex of the finger.