The red cell represents a useful model for the study of general pathophysiological mechanisms, because of its availability and the relative easiness of the methodological approach due to the absence of nucleus and organelles. Particularly, most of the transmembrane ion transport systems, which control the homeostasis of intra- and extracellular electrolytes, have been firstly discovered in the red cell membrane. The pathophysiological importance of these transport systems is often extended to non haematological diseases like essential hypertension. Several reports from different laboratories have established that the red cell Na+/Li+ countertransport is stimulated in patients with essential hypertension. The regulation of Na+/Li+ countertransport, relationship with plasma and membrane lipids and the possibility of modulating its activity by dietary interventions, are focused in the last part of this review.