Artificial Intelligence in the healthcare sector has been highlighted as a key technology to tackle the major challenges facing healthcare systems today. ChatGPT, a large language model developed by OpenAI, shows promise as a support tool for healthcare workers. This study investigates the adoption and usage of ChatGPT among medical doctors in the Philippines by utilizing an integrated theoretical framework combining Task-Technology Fit (TTF) and Unified Theory of Acceptance and Use of Technology (UTAUT). A total of 279 licensed medical doctors in the Philippines participated in an online survey through convenience sampling. Structural equation modeling was used to analyze the relationships among constructs. Performance Expectancy and Social Influence emerged as positive significant factors of Behavioral Intention to Use. Furthermore, Task Technology Fit and Behavioral Intention to Use significantly influenced Actual Use of ChatGPT by medical doctors. The findings emphasize the importance of understanding the influencing factors in usage intention and the task-technology alignment of AI tools in driving adoption. The study provides empirical insights into exploring the potential role of ChatGPT in healthcare and discusses theoretical and practical implications.