Crescentic glomerulonephritis provides an important therapeutic challenge because of its rapidly progressive course and poor outcome. Studies in animal models have elucidated some of the pivotal pathogenetic mechanisms, and human studies increasingly support the clinical relevance of these animal data. Accumulating evidence suggests that crescentic glomerulonephritis results from a complex cell-mediated nephritogenic immune response. Interruption of a number of immune and inflammatory mediators can improve the outcome of this disease.