Background Different patterns of stress shielding may lead to differences in periprosthetic bone preservation around cemented and uncemented hips in the long term? Questions/purposes The purpose of this study is to compare the difference in periprosthetic bone density between cemented Charnley total hip and uncemented hydroxyapatite-coated Furlong 1 THAs at a minimum followup of 12 years (mean, 16 years; range, 12-24 years). Methods We studied a cohort of 17 patients who had bilateral THAs with a cemented Charnley THA on one side and an uncemented Furlong 1 hydroxyapatite-coated THA on the other side. At a minimum followup of 12 years, Harris and Oxford hip scores were used to determine the function, and dual-energy x-ray absorptiometry was used to quantify bone mineral density adjacent to the prosthesis.The results of the dual-energy x-ray absorptiometry scan for cemented and uncemented hips were analyzed using paired-sample two-tailed t-tests. To compare the Harris hip scores, a nonparametric Wilcoxon test was used.