Osteon population densities (OPDs) were determined from transverse sections removed from an area immediately adjacent to the sternal ends of 60 autopsy rib samples. The samples ranged in age from 11 to 88 years. Regression analysis was performed using age at death as the dependent variable an OPD as the independent variable. The results of the training set/test set strategy to evaluate the performance of the histological age predicting model indicated that it provides reasonably reliable and accurate age estimates. A multiple regression model using both OPD and the mean age for a rib's morphological age according to the phase method of Iscan and others is also presented. This later age predicting model is recommended when both methods are applicable. Figure, tables, and 18 references (Author abstract modified)