The present study investigated the influence of hydrostatic pressure on the expression of interleukin-8 (IL-8) in a human chondrocyte-like cell line (HCS-2/8). The cells were exposed to hydrostatic pressure (1, 5, 10, or 50 MPa) by a special apparatus. Total RNA was extracted, and was analyzed by a polymerase chain reaction method for IL-8 mRNA. IL-8 concentrations in a culture medium were assessed by ELISA. The expression of IL-8 mRNA was enhanced after exposure to 50 MPa of hydrostatic pressure. IL-8 level in a culture supernatant increased following 50 MPa of pressure. Increased IL-8 production in the present study is an important point when we consider the pathology of inflammatory joint diseases, and this point also shows that treatment which reduces mechanical loading could improve, or slow the progression of, joint diseases.