Recently, several authors have reported about some growth factors and leukins as a factor of cholesteatoma-induced bone resorption. Parathyroid hormone related protein(PTHrP) has potent PTH-like bioactivities and it is responsible for both bone resorption and cell growth. The biologic hallmarks of cholesteatoma are specially invasiveness and uncontrolled proliferation. These characteristics suggest a fundamental alteration in normal biology of one or more at cellular constituents like fibroblast and keratinocyte. In an attempt to define alteration of biologic characteristic in culture medium, PTHrP production of fibroblasts from human cholesteatoma was compared to the cells from previously established cholesteatoma cell line, keratinocytes and fibroblasts from normal and pathologic skin by means of radioimmunoassay. Fibroblasts established from cholesteatoma specimens were very similar to fibroblasts from skin in morphological study, however there were some differences between fibroblasts from cholesteatoma and normal dermal fibroblasts. The concentrations of PTHrP in conditioned media were higher in the fibroblasts from cholesteatoma than in those cells from other skin diseases. These results demonstrated that biologic characteristic of cholestratoma fibroblasts was different from that of normal dermal fibroblasts. Cholestratoma fibroblasts could contribute to produce PTHrP which is known to induce bone destruction and abnormal cell growth during progress of disease.