This article reports the results of neurobehavioral tests on C(5)-C(10) normal paraffinic constituents (n-paraffins). Shortly after exposure, effects were evaluated in several domains including clinical effects, motor activity, functional observations, and visual discrimination performance. The representative C(5) n-paraffin, n-pentane, did not produce any evidence of acute central nervous system (CNS) effects at levels up to 20 000 mg/m(3). Similarly, there was no compelling evidence that n-octane (C(8)) produced CNS effects at 14 000 mg/m(3), the highest concentration tested. n-decane (C(10)) produced minor, reversible acute CNS effects at 5000 mg/m(3), with 1500 mg/m(3) as the no-effect level. Consistent with literature data, there seemed to be a relationship between increasing molecular weight up to C(10) and acute CNS effects. However, the CNS effects were reversible. Repeated exposures did not provide evidence of metabolic induction.