To determine the usefulness of recognizing the different morphologic patterns of chronic active liver disease (CALD), we compared clinical and biochemical features as well as responses to treatment in 32 patients with chronic active hepatitis (CAH); 36 with subacute hepatitis and bridging necrosis (SHB); 30 with subacute hepatitis and multilobular necrosis (SHMN); and 30 with cirrhosis and active hepatitis (Cirrh). The morphological lesions did not correlate with clinical or etiologic features. Patients with CAH had less severe biochemical abnormalities, entered remission more often, and failed to respond to treatment less frequently than those with SHMN or Cirrh. SHB and SHMN resembled each other in many regards and showed greater functional changes than CAH. Cirrhosis developed more often after SHMN than CAH and was associated with a poorer prognosis than CAH. Serial liver biopsies revealed all possible histologic transitions, with reduction of inflammation usually occurring in patients treated with steroids and extension of inflammation being more frequent in those not receiving these drugs. CAH, SHB, SHMN, and Cirrh, therefore, reflect the degree and extent of disease activity at any given time in CALD, rather than representing different conditions. Identification of the initial morphologic lesion is helpful because of differences in prognosis.