The cellular composition of 33 solid and cystic periapical granulomas was quantitated by a differential morphometric technique. Macrophages were the predominant inflammatory cell, followed in descending numerical order by lymphocytes, plasma cells, and neutrophils. Inflammatory cells comprised slightly more than half the formed elements; the others were connective tissue elements. There were no significant qualitative or quantitative differences in the inflammatory components of lesions differing in morphology (solid vs cystic), symptomatology (pain vs no pain), duration (less than one year vs more than one year), and treatment (endodontic intervention vs no intervention). The human periapical granuloma thus reflects a complex of immunologic and nonimmunologic inflammatory reactions.