Surgical closure of an external naris reduces airflow through one side of the nasal cavity. Previous studies using [3H]thymidine autoradiography have demonstrated that rats subjected to the procedure on Postnatal Day 1 (P1) exhibit reduced cellular proliferation in the olfactory mucosa by P30. We investigated cell production at earlier ages to determine (a) when the effect first emerges, and (b) whether septal, dorsal, and lateral regions of the nasal cavity responded similarly. Both short (2-h) and long (30-day) survival groups were tested. Results from the first group indicate that changes in proliferation emerge between P10 and P20, and that the septum is more affected than other regions of the nasal cavity. No differences were observed in the long survival groups, perhaps due to changes in patterns of cell production or death.