Littermate rat pups underwent either unilateral surgical occlusion of the right external naris or sham surgery on postnatal Day 1. At 4-, 8-, 12-, 20- or 30-days postpartum, olfactory bulb sections were histochemically reacted to reveal either succinate dehydrogenase (SDH) or cytochrome oxidase (CO) activity. Microdensitometry was used to determine levels of staining in glomeruli and the external plexiform layer at standardized locations within the bulb. In experimental subjects asymmetries in left/right bulb SDH staining patterns were detected as early as Day 4, suggesting that the deprivation procedure resulted in quite rapid changes in the metabolic function of olfactory bulb cells. Control animals did not exhibit left/right differences in bulb staining, but inter-glomerular and regional variations in staining were observed throughout the early developmental period. Understanding these early variations in metabolic activity may be important for a complete understanding of olfactory bulb maturation.