Referring to the mosaic theory of Page, the authors present an overview of recent topics related to the participation of endocrine and auto-paracrine factors, such as steroids, ouabain-like substance, insulin, renin-angiotensin and endothelin, in the pathogenesis of primary hypertension. These factors promote the development of hypertension in either a direct or indirect manner; in addition, they promote, to some extent, the proliferation of vascular smooth muscle cells. Future research should attempt to elucidate interactions between these factors in cardiovascular tissues and to define how these factors interact with various vasodepressor substances to regulate blood pressure. (Hypertens Res 1995; 18: 171-179)