We evaluated the use of a hemipelvic acetabular transplant in 20 revision hip arthroplasties with massive acetabular bone defects. We report 65% good intermediate-term results at a mean follow-up of 5 years (4-10 years). A cemented cup (without a reinforcement ring) was entirely supported by the allograft in all procedures. There were 7 failures (5 aseptic loosening and 2 deep infections). Two dislocations occurred but did not require acetabular revision. There were 2 cases in which moderate acetabular migration occurred but then stabilised and did not progress. Thirteen of 20 acetabular reconstructions did not require revision. We believe that these are satisfactory intermediate-term results for massive acetabular defects too large for reconstruction with other standard techniques.