The effect of a vitamin D deficient (--D), vitamin D replete (150 I.U. D3 twice weekly) and normal rat diets for 4 weeks in weanling male rats on the steady-state concentration in several brain sites of dopamine (DA), norepinephrine (NE), and dihydroxyphenylacetic acid (DOPAC) was investigated. The areas of the central nervous system assayed were the brainstem, cerebellum, cerebral cortex, hypothalamus-median eminence, and striatum. The results indicate that DA content of cortex and hypothalamus significantly increased in the --D group compared to the normal diet or D replete groups. The concentrations of DOPAC and NE in the cortex of both --D and D replete rats increased significantly compared to normal diet group. Plasma calcium level was significantly lower in --D group compared to the normal diet or vitamin D replete groups.