The CCIS book constitutes selected papers of the 12th International Conference on Computational Science and Computational Intelligence, CSCI 2025, which took place in Las Vegas, NV, USA, during December 3 5, 2025.

A total of 42 papers were selected for inclusion in this book from the following tracks: 29 papers were selected from 168 submissions to the Research Track on Health Informatics and Medical Systems, CSCI-RTHI; 13 papers out of 294 submissions to the Research Track on Large Language Models, CSCI-LLM.

The papers were organized in topical sections as follows: Health Informatics, Medical Devices, Disease Diagnosis, and Applications; Health Informatics, Artificial Intelligence, and applications; Health Informatics, Data Science, Prediction Methods, Applications and Tools; Large Language Models and Applications in Health; Large Language Models and Applications in Education; and Poster Papers.