This study aims to determine the incidence and factors associated with pyrexia following total knee replacement (TKR). We performed a retrospective analysis of the temperature charts and histories of patients who underwent 170 TKRs. There was a statistically significant increase in mean temperature from pre-operation to post-operation, and this increase remained significant through to 5 days post surgery (por=38 degrees C) at some point. Fourteen patients developed a clinical infection, but only four of these were pyrexial. There was no association between pyrexia and infection, allogenic blood transfusion, haemoglobin loss, use of urinary catheter, rheumatoid arthritis, anaesthetic type, and previous pyrexia following TKR. Pyrexia as a diagnostic test for the development of infection had a sensitivity of 0.286 (95% CI=0.084-0.581), specificity of 0.628 (95% CI=0.548-0.704) and positive predictive value of 0.065 (95% CI=0.018-0.157). Pyrexia in the first 5 days following TKR is usually a normal physiological response and should not cause undue concern about the presence of infection.