Abnormalities of cell number are a frequent feature of renal disorders. Cell death is a key factor in the regulation of cell number. Apoptosis is an active form of cell death that is modulated by extracellular lethal and survival signals. Regulation of apoptosis also involves a complex system of sensors of the extracellular signals, triggers of the apoptosis program, effectors of apoptosis as well as intracellular survival factors. This paper first reviews current knowledge on the regulation of apoptosis with particular emphasis on renal cell death. Subsequently, it deals with the role of apoptosis in triggering renal disease and its participation in the progression and resolution of renal disorders. This section includes information on the occurrence of apoptosis and expression of apoptosis-related genes in glomerular injury, acute renal failure, chronic renal atrophy, renal fibrosis, polycystic renal disease and kidney development. The final section presents an overview of possible approaches to the therapeutic manipulation of apoptosis in the kidney.