We investigated whether information on concentrations of the trace metals in cerebrospinal fluid of patients with viral meningitis could be of value in diagnosis or prognosis. Samples from ten patients and 11 control subjects were analysed for zinc, copper, and manganese by atomic absorption spectrophotometry method. Protein concentrations in cerebrospinal fluid were also determined. The mean pretreatment values of zinc and copper were significantly lower (p<0.05 and p<0.01, respectively) than those of control subjects and returned to the control value after treatment. The mean pretreatment value of manganese was significantly lower (p<0.001) than the control value and became still lower (p<0.01) after treatment. The estimation of the trace metals in cerebrospinal fluid of patients with viral meningitis is very helpful to determine the diagnosis and prognosis.