Our aim was to determine if the serum levels of bone-resorbing cytokines (IL-1beta, TNF-alpha, IL-6, GM-CSF) are altered in patients with aseptic loosening of a total hip prosthesis, and if such levels are influenced by the type of implant. We determined cytokine levels in sera from 35 patients before revision for failed total hip arthroplasty and compared them with those in 25 healthy donors. We also assessed the soluble receptor of interleukin-2 (sIL-2r) in serum as an indication of a specific immune reaction against the implant. Our findings showed that the sIL-2r and TNF-alpha serum level did not change. The IL-6 level was not significantly altered, but was higher in patients with TiAIV prostheses than in those with a CrCoMo implant and in patients with cemented prostheses. The IL-1beta level was found to be higher in those with a TiAIV cemented prosthesis than in the control group (p=0.0001) and other groups of patients (p=0.003 v uncemented TiAIV, p=0.01 v cemented CrCoMo, p=0.001 v uncemented CrCoMo). The GM-CSF level significantly increased in patients compared with healthy subjects (p=0.008), and it was higher in those with cemented than with uncemented implants (p=0.01). Only patients with cementless CrCoMo prostheses had levels of GM-CSF similar to those of the control group. The highest GM-CSF concentrations were observed in patients treated with non-steroidal anti-inflammatory drugs (NSAIDs) in the last months before revision (p=0.04). In addition, when massive osteolysis was observed, the level of GM-CSF tended to decrease to that of the control group.