['Clinical coding data provide the basis for Hospital Episode Statistics and Healthcare Resource Group codes. High accuracy of this information is required for payment by results, allocation of health and research resources, and public health data and planning. We sought to identify the level of accuracy of clinical coding in general surgical admissions across hospitals in the Northwest of England.', 'Clinical coding departments identified a total of 208 emergency general surgical patients discharged between 1st March and 15th August 2013 from seven hospital trusts (median = 20, range = 16-60). Blinded re-coding was performed by a senior clinical coder and clinician, with results compared with the original coding outcome. Recorded codes were generated from OPCS-4 & ICD-10.', 'Of all cases, 194 of 208 (93.3%) had at least one coding error and 9 of 208 (4.3%) had errors in both primary diagnosis and primary procedure. Errors were found in 64 of 208 (30.8%) of primary diagnoses and 30 of 137 (21.9%) of primary procedure codes. Median tariff using original codes was £1411.50 (range, £409-9138). Re-calculation using updated clinical codes showed a median tariff of £1387.50, P\xa0=\xa00.997 (range, £406-10,102). The most frequent reasons for incorrect coding were "coder error" and a requirement for "clinical interpretation of notes".'] Is improving accuracy of clinical coding in surgery : collaboration key?