We compared the prevalence of periglenoid radiolucencies between two glenoid component preparation techniques used in total shoulder arthroplasties. Seventy-two consecutive patients with primary osteoarthritis had total shoulder arthroplasties using one prosthetic system with flat-back keeled polyethylene glenoid components. Thirty-seven shoulders had glenoid implants that were cemented after standard curettage preparation of the keel slot. Thirty-five shoulders had glenoid implants that were cemented after using bone compaction to prepare the keel slot. The immediate postoperative and 2-year postoperative radiographs were examined to evaluate the presence and progression of periglenoid radiolucencies. The curettage group had a higher rate (38%) of keel radiolucencies than the compaction group (11%) seen on the immediate postoperative radiographs. Both groups had progression of periglenoid radiolucencies with time. Progression of the radiolucent lines was worse in the curettage group 2 years after arthroplasty. Preparation of the glenoid component keel slot with the bone compaction technique seems to achieve better fixation of flat-back keeled polyethylene glenoid components in total shoulder arthroplasties.