The vibration spectra of a pneumatic hammer, Atlas Copco BHV-type, was analyzed from the wrists of workers and from the tool during use. Men (16) who were exposed to the vibration of the tool were examined for hand-arm symptoms associated with vibration. The left hand, holding the chisel head, could be more affected than the right hand, holding the barrel of the hammer. The asymmetry in symptoms between the left and right hands was examined on the basis of history, a clinical examination and a cold provocation test. The vibration from the chisel head of the tool was of a higher frequency than that from the hammer. The vibration acceleration was 1000-fold greater in the chisel head than in the barrel of the hammer, and it was higher in the frequency range from 100-1000 Hz. The left hand was more affected on the basis of the workers'' history and the cold provocation test. This asymmetrical exposure is very rare today, and the differences in the severity of symptoms between the left and right hands are mild, although the history of these workers indicate that the symptoms were grossly asymmetrical 10-20 yr ago when asymmetrical exposure was common.