Computer technology has brought about incredible changes in medicine and healthcare, greatly improving the efficiency and accuracy of medical treatment. Since December 2019, in the face of the global effects of COVID-19, the significance of computer technology, and big data in particular, together with the collaborative network and unmanned technology, has been recognized by healthcare staff everywhere. Modern medical science cannot evolve without the involvement of computer science. This book presents the proceedings of the 2021 Workshop on Computer Methods in Medicine & Health Care (CMMHC 2021), the autumn edition of the TDI conferences, held as a virtual, online event on 24 – 26 September 2021. Researchers from renowned universities, laboratories and hospitals in China, Italy and Japan contributed to the workshop, and findings from both basic and clinical medicine are included in the 14 papers collected here. Big data technology appeared in 20% of all papers as the most popular topic, with one paper covering big data optimization and two describing its application. The book shares practical experiences and enlightening ideas from computer-based medicine and will be of interest to researchers in and practitioners of modern medicine everywhere.