We evaluated a patient in whom pachydermoperiostosis occurred in conjunction with anemia and gastric hypertrophy. The mechanism of the anemia appears multifactorial because, besides a myelofibrosis, a serum inhibitor of the late stage of erythropoiesis was detected. The elevated serum bone Gla-protein (osteocalcin) favors the hypothesis that primary hypertrophic osteoarthropathy represents an imbalance between increased osteoblastic bone formation and normal bone resorption.