Life implies organization and thus regulation. This requires intraand intercellular communication and communication with the environment. The exchange of information is to a large extent based on messenger molecules with the capacity to interact selectively with and to activate particular molecular receivers, the receptors. Receptor dysfunction may be a factor in the aetiology of various diseases. Receptor research has evolved to a separate discipline “receptorology”. This should not hamper the development of applied or clinical receptorology. Various aspects thereof are discussed such as: inborn errors of receptor function, receptor-autoimmune diseases, receptors and cancer, iatrogenic receptor imbalance, receptor histochemistry, receptors and targeting of drugs, and radio-receptor assay. Attention is paid to receptor differentiation and particularly to receptor denomination. Here for practical reasons a self-evident, rational, and simple system is required. Receptorology may, even more than enzymology, contribute to a reintegration of various physiological disciplines, including biochemistry, endocrinology, immunology, neurology and particularly also pathology, leading to molecular physiology. The adaptation of methods and techniques common in receptor research to the needs of clinical sciences is an important step in that direction.