The nasal passages of rodents provide valuable opportunities for research on relationships between cell proliferation and cancer. The nose, which has multiple functions, possesses a diverse range of tissue types, each with its own morphologic, physiologic, and metabolic characteristics and site-specific cell turnover rates. Moreover, for inhaled materials deposited in the nose, complex regional uptake or deposition patterns can result in site-specific responses, including cancer. Presented here are important criteria necessary for undertaking cell proliferation studies in the nasal passages. The current literature concerning nasal toxicity and the toxicant-induced proliferative response are also reviewed. Rodent nasal epithelium provides a fruitful area for research on the role of cell proliferation in carcinogenesis.