User Centered Design (UCD) is widely used in computer science and service provision, not so in public health administration. As a regulatory body (e.santé Occitanie) we applied UCD to design, deploy and assess a new medical service (ambulatory ECG at the local medical practice) at the request of a local general practitioner (GP). Method. We used semi-directed interviews starting with the GP to define the user groups profiles, as-is scenario and personae. We organized a focus group with the local stakeholders and representatives of Social Security, Regional Health Agency and e.santé Occitanie to refine the expression of needs. We used a SWOT to categorize the internal and external factors impacting the service. We designed a first specification prototype and a preliminary assessment of additional costs from the point of view of the Social Security. When the service started we arranged an 8-week prospective survey to verify the medical indications adhered to best practices. We ran an observational costs analysis on the first full year of operation. Results. As the study started in 2018 we had to cope with COVID 19 induced delays and changes. End of 2021 we could observe the start of the operation of the optimized version of the service with 4 steps instead of 9 in the as-is version. The 8-week medical indication survey showed full compliance with best practices. In 2022, first full year of operation, 39 patients had an AECG, less than expected, probably due to a waiting list effect. The additional costs analysis gave a benefit for Social Security of 12,397.05 € at 95% of expectations. After absorption of investment costs, expected benefit is 16,479.45 € at 98%. Conclusion. As a regulatory body, we successfully implemented the full UCD cycle on a bottom-up medical service improvement proposal. The service is still operating and has been spontaneously adopted elsewhere. UCD applied to selected local proposals could unveil a wealth of quality of care improvement solutions while keeping the costs down.