An immunoperoxidase method using Coxiella (C.) burnetii-specific hyperimmune serum raised in rabbits, and swine anti-rabbit horseradish peroxidase conjugate was applied to visualize C. burnetii in BGM cell cultures. The technique proved to be highly specific and did not result in any unspecific background staining. The technique was applied successfully to study the organism during multiplication in vacuoles of epithelial cells and in the phagolysosomes of macrophages. Preliminary results further indicate that the technique may be useful for the detection of the pathogen in tissues and milk samples.