Twenty-eight bone specimens containing the implant beds of partial and total hip arthroplasties were studied. All cases of infection of the prosthesis bed and of pathological fractures due to metastasis were excluded. There was necrosis around the acrylic cement (up to three weeks postoperatively), followed by repair of the implant bed (up to two years postoperatively), and finally by bone remodeling (after completion of the repair). Microscopic acrylic pearls were found in the implant bed, documenting possible harmful alterations of the cement surface. Early and late loosening of the prosthesis may be associated with characteristic changes of the implant bed.