In this pilot study, we examined the effect of the intravenous administration of delta-9-tetrahydrocannabinol (THC) on the activity of spontaneously active A10 dopamine (DA) neurons of anesthetized, male albino rats. This was accomplished using the technique of in vivo extracellular single-unit recording. The administration of THC (0.05–1.6 mg/kg i.v.) did not significantly alter either the basal firing rate or the firing pattern of spontaneously active A10 DA neurons compared to vehicle controls. Our findings suggest that, unlike a number of drugs of abuse, THC does not alter the activity of A10 DA neurons and that the previously reported THC-induced increase in brain DA levels is not due to its action on firing rate or pattern in A10 DA neuron