The importance of membrane transport in normal physiological cell function is unquestionable. However, to what extent alterations in the transport of amino acids are the cause and / or consequence of pathological changes observed in disease states is a question not yet completely clarified. Kinetic experiments with blood cells provide a simple and useful model for researching alterations in amino acid transport. The cationic amino acid L-arginine is the precursor of nitric oxide (NO), a key second messenger involved in functions such as endothelium-dependent vascular relaxation, immune defence and platelet activation. The transport of L-arginine, being rate-limiting for nitric oxide production, is extremely relevant to pathological conditions where NO synthesis and / or actions are affected. The current review provides an overview of L-arginine transport in disease, specifically in uraemia, heart failure, hypertension, diabetes mellitus, septic shock and sickle cell disease.