To examine how the severity of postoperative pain affects patient's health-related quality of life (HRQoL) at 1 week following surgery and to compare two generic validated HRQoL instruments.; Patients undergoing general or orthopaedic surgery at the Royal London Hospital were randomly sampled. The following patient outcome data were collected EQ-5D (EuroQoL) pre-operatively and the Revised American Pain Society Patient Outcome Questionnaire (APS-POQ-R) at 24 hours postoperation; and EQ-5D, Short-Form-12 (SF-12) and APS-POQ-R at 7 days postoperation. The degree of association between pain and HRQoL was assessed using Pearson's correlation coefficient and multivariate generalized linear regression models.; Of the 228 patients included, 166 patients provided data at 7 days. Sixteen percent reported severe pain ≥ 50% of the day at 7 days. The severity of pain on both the APS-POQ-R pain severity and interference and affective impairment domains at 7 days was highly correlated with a decrease in HRQoL as assessed by the SF-12 Physical Component Score (PCS), SF-12 Mental Component Score (MCS), and EQ-5D scores (r = -0.34 to -0.61, P < 0.0001). Multivariate regression analyses showed that irrespective of confounding factors (eg, age, gender, and pre-operative HRQoL) patients with severe postoperative pain experience important reductions in both physical and mental well-being domains of their HRQoL.; A proportion of patients continue to experience severe pain at 7 days postoperatively, even after minor surgery. HRQoL is strongly associated with the level of pain and provides additional data on the impact of postsurgery pain on patient's function and well-being. Additional studies are needed to elucidate the interaction between pain severity and HRQoL during the peri-operative period.