The monoterpenes limonene and perillyl alcohol have been shown to induce the complete regression of rat mammary carcinomas by what appears to be a cytostatic and differentiation process. In order to evaluate the differentiating effects of the monoterpenes we tested the ability of perillyl alcohol to induce differentiation in a well-characterized neuroblastoma cell model. Perillyl alcohol was found to be a potent inducer of the neuroblastoma-derived cell line Neuro-2A. Several cellular effects of monoterpenes were ruled out as contributing to Neuro-2A differentiation including its cytostatic effect and its ability to inhibit ubiquinone (CoQ) syntheses.