ChatGPT, a language model developed by OpenAI, has been tested in several medical board examinations. This study aims to evaluate the performance of ChatGPT on the Portuguese National Residency Access Examination, a mandatory test for medical residency in Portugal. The study specifically compares the capabilities of ChatGPT versions 3.5 and 4o across five examination editions from 2019 to 2023. A total of 750 m...