We want to address the clinical issue of too sparse supply of allograft in total hip replacement and ambitions of controlling the grain size distribution. Bioglass BAG-S53P4 was evaluated as a bone graft additive to chemically treated allografts with controlled grain size distribution. Allografts were chemically cleaned (CG) and mixed with BAG-S53P4 additive (BG) for comparison. All samples were compacted with a dropped weight apparatus and then underwent a uniaxial compression test. The yield limit was determined by a uniaxial compression test and density was recorded while flowability was calculated. There was no difference between the yield stress limit of BG and CG after compaction (p = 0.432). Adding BAG-S53P4 reduced flowability and could indicate better interlocking mechanism between particles. Adding BAG-S53P4 seems to have no impact on the yield stress limit. The extended allografts withstand the compaction equally good which makes it a valid bone substitute in total hip replacement. An in vivo loaded study is needed before clinical use can be recommended. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1875–1879, 2015.