Abstract.Clinical and laboratory findings and drug history were studied in 17 patients with suspected hydralazine‐associated nephritis, five of whom only had renal disease, while twelve also had extrarenal manifestations. Renal biopsies revealed extracapillary proliferative or focal segmental proliferative glomerulonephritis in 10 patients, and tubulo‐interstitial nephritis in five patients. Antinuclear antibody (ANA) was found in 16 patients, but none of the 14 patients tested had antibodies to DNA. Tests for antibodies to myeloperoxidase (anti‐MPO) and antibodies to neutrophil cytoplasm antigen (ANCA) were performed by ELISA. Twelve of the 14 patients tested had anti‐MPO; five of these 14 patients had ANCA, while one had borderline levels. These findings suggest that hydralazine facilitates the induction of a systemic disease with multiple autoantibody pro