Using general practitioner records, hospital medical notes and through direct telephone conversation with patients, we investigated the accuracy of nine patient-reported complications after elective joint replacement surgery of the hip and knee. A total of 402 post-discharge complications were reported after 8546 elective operations that were undertaken within a three-year period. These were reported by 136 men and 240 women with an overall mean age of 71.8 years (34.3–93.2). A total of 319 (79.4%; 95% confidence interval, 75.4%–83.3%) reported complications were confirmed to be correct. Very high rates of correct reporting were demonstrated for infection (94.5%) and further surgery (100%), whereas the rates of reporting deep venous thrombosis (DVT), pulmonary embolism, myocardial infarct and stroke were lower (75%–84.2%). Dislocation, periprosthetic fractures and nerve palsy were associated with modest rates of correct reporting (36%–57.1%). More patients who had had knee surgery delivered incorrect reports of dislocation (p = 0.001) and DVT (p = 0.013). Despite these variations in accuracy, it appears that post-operative complications may form part of a larger patient-reported outcome programme for monitoring outcome after elective joint replacement surgery.