High levels of dietary calcium attenuate the elevation of arterial pressure induced by deoxycorticosterone (DOC)-salt in trained, conscious dogs. This response resulted primarily from the failure of the expected rise in peripheral vascular resistance to develop. In addition, the enhanced pressor sensitivity to norepinephrine and angiotensin II associated with DOC-salt hypertension was normalized by high levels of dietary calcium. These changes could not be explained by changes in serum potassium concentration, plasma catecholamines concentration, or plasma volume. A possible explanation is that high levels of dietary calcium inhibit a parathyroid hypertensive factor that has been observed to be elevated in mineralocorticoid-induced hypertension. This hypothesis requires further studies.