At a mercury spill, several workers were exposed to mercury vapour concentrations up to 0.15 mg/m3. Two weeks after, 38 exposed workers were examined. Fourteen had a Hg in urine concentration above 25 nmol/l. Two exposed groups (n = 7) and an unexposed control group (n = 15) were formed, based on Hg in urine: a HI group with mean = 106.5 nmol/l (range: 49.5-249); a LO group with mean = 35.2 nmol/l (range: 28.8-48.0), and control group with mean = 10.5 nmol/l (range: 4.5-14.1). The groups were reexamined 3 and 16 months later. The groups were examined with two computer-based portable test systems. CATSYS quantifies hand pronation/supination, finger tapping, and reaction time. TREMOR records and analyses tremor at the finger tips. The results showed reduced coordination ability in the HI group at the first examination compared to the control group. Tremor intensity was very high in the HI group and decreased only slightly during the follow-up period. The study indicates that quantification of coordination ability and tremor intensity can be used within occupational medicine for the assessment of the impact of acute mercury intoxication.