1. Both animal and clinical studies clearly suggest a close link between dopamine production and renal delivery of sodium. 2. It appears that tubular transport of sodium and DOPA could represent the rate limiting step for the renal synthesis of dopamine; the membrane transport mechanism is sensitive to the nucleotide cyclic GMP. 3. In sodium overloaded animals AAAD activity appears to be greater than that in controls, but the tubular transport of L-DOPA might be decreased. 4. Since the final product of an increased sodium delivery to the kidney is an increased urinary excretion of dopamine, it might be hypothesized that the outward transport of newly formed dopamine in tubular epithelial cells is also affected by high tubular sodium.