The term acute postinfectious glomerulonephritis includes a large group of glomerulonephritis that result from a variety of infectious agents. In this chapter we will deal only with the most common glomerulonephritis that result from bacterial infections. The term acute glomerulonephritis defines a pathological process that may be manifested clinically as an acute nephritic syndrome, nephrotic syndrome or rapidly progressive glomerulonephritis. Since post-streptococcal glomerulonephritis is the best known of the acute postinfectious glomerulonephritis and its most frequent clinical picture is the acute nephritic syndrome, the terms poststreptococcal glomerulonephritis, acute glomerulonephritis and acute nephritic syndrome are often, and incorrectly, used interchangeably.