Multivariate analysis of covariance found statistically significant differences in age-adjusted histomorphological variables between the fourth ribs of males and females, indicating that gender is an important factor in bone remodeling and osteon population density. Also, bone loss is exacerbated by the increased activity rate of basic multicellular units caused by menopause in middle-aged women. The possible reason for sex differences for all histomorphological variables in 40-49 year-olds could be female menopause. In addition to menopause, other physiological factors that could cause differences in histomorphological features of bone between males and females must be further explored. When the sex of skeletal remains can be assumed through other anthropological analysis, the use of the age-predicting equation for a known sex in this study would produce a more reliable result than the equation for unknown sexes. Two thin sections per sample were prepared by manual grinding. Histomorphological features were assessed from the sternal end of the fourth rib from a wide age range. All subjects had died suddenly and had no history of chronic illness. The age range of the males was 22-67 years, and the age range of the females was 20-60 years old. The following variables were measured using an Olympus BX-51 light microscope with simple polarizing attachment and image analysis solutions: cortical area, relative cortical area, intact osteon density, fragmentary osteon density, osteon population density, average osteon area, and average Haversian canal area. 7 tables, 2 figures, and 13 references