Until relatively recently, the cerebellum was considered primarily as modulator of fine motor functions. This has changed during the last 20 years, and now the cerebellum has been shown to be involved in learning and cognition. With this renewed interest comes the need to better understand and potentially modify its input-output connections. In this pilot study, we tested the efficacy of a canine adenovirus type 2 (CAV-2) vector in the cerebellum of a nonhuman primate (NHP). Consistent with other reports, we found a preferentially transduction of cells with neuron-like morphology at the site of injection and efficient retrograde transport into several structures in the midbrain. These data will help identify cerebellar circuits and may lay the foundation for studies of human pathologies, such as ataxias, autism, and schizophrenia.