Eighteen liver and seven bone marrow biopsies from 44 patients with clinically and serologically proven Q-fever seen during a recent outbreak were studied. Highly distinctive fibrin-ring granulomas were found in seven liver and four bone marrow specimens. Lipid or nonspecific granulomas often containing neutrophils and variable numbers of giant cells were noted in 13 livers and seven bone marrows. A wide variety of nongranulomatous histological changes, frequently including steatosis and nonspecific "reactive" hepatitis, were seen in the liver biopsies. Identifiable rickettsiae were not present in tissue sections studied by microbiologic stains or electron microscopy. The histological response pattern to Coxiella infection is varied, and Q-fever should always enter the differential diagnosis of a granulomatous disease encountered in liver and bone marrow specimens.