Seven cases of peripheral and five cases of central giant cell granulomas were evaluated for the detection of estrogen receptor proteins using immunohistochemical analysis. Strong positive staining was observed in the multinuclear cell population in five cases of peripheral giant cell granuloma. The mononuclear cell population was weakly positive in all cases. Estrogen receptor immunoreactivity was negative in all cases of central giant cell granulomas. It is well known that both peripheral and central giant cell granulomas of the jaws have a distinct female predilection. Our findings suggest that only the peripheral giant cell granuloma may be partially under hormonal influence.