Objective. Electronic medical records (EMRs) have not developed much beyond the days of typewritten journals when it comes to facilitating extraction of data for quality assurance (QA) and improvement of health-care performance. Material and methods. Based on 5 years’ experience from the Norwegian Gastronet QA programme, we have developed a highly QA-profiled EMR for colonoscopy. We used a three-tier solution (client, server and database) written in the Java programming language using a number of open-source libraries. QA principles from the Norwegian paper-based Gastronet QA programme formed the basis for development of the ColoReg software. ColoReg is developed primarily for colonoscopy reporting in a screening trial, but may be used in routine clinical work. The QA module in ColoReg is well suited for intervention towards suboptimal performance in both settings. Results. We have developed user-friendly software dominated by clickable boxes and curtain menus reducing free text to a minimum. The software gives warnings when illogical registrations are entered and reasons have to be given for divergence from software recommendations for work-up and surveillance. At any time, defined performance quality parameters are readily accessible in tabular form with the named, logged-in endoscopist being compared with all other anonymized endoscopists in the database. Conclusion. The ColoReg software is developed for use in an international, multicentre trial on colonoscopy screening. It is user-friendly and secures continuous QA of the endoscopist's performance. The principles used are applicable to development of EMRs in general.