Hans Peterson was born in 1928 in the city of Karlskoga, Värmland county, the hometown of Alfred Nobel. He moved to Stockholm for studies at the Institute of Electricity at the Royal College of Technology. However, he could soon fulfill his dreams of medical studies and moved to the Karolinska Institute. During the summer of his third year of medical studies, he had a temporary position in the chemical laboratory at the Roslagstull hospital in Stockholm. In collaboration with the Sahlgrenska hospital, Göteborg, a project had been started to automate laboratory analyses. This was the start of Hans’ development from basic machine coding to advanced informatics.

When he had achieved his MD he decided to specialise in ophthalmology. During this part of his education, he started a scientific project concerning screening the health of Swedish soldiers. Initially, this work was recorded on punched cards, but during his doctoral studies from 1963, the possibility to transfer data to magnetic tape arose. The result of his scientific work was presented in 1968, and as Ph.D., he planned to make an academic career in ophthalmology.

In 1970 the Stockholm county enrolled Hans in the long-term work of digitalisation of the county operations. At that time, he got acquainted with Paul Hall, one of the great Swedish pioneers in electronic record development. Hence Hans became engaged in the early development of medical informatics, and he became one of the first members of the Swedish Society of Medical Informatics.

Hans’s degree in ophthalmology was converted to a degree in medical informatics by Karolinska Institute, and by that he can be considered as the great health informatician in Sweden. Not only Swedish informatics has been promoted by him; he was also one of the main initiators of the European Federation for Medical Informatics which celebrates its 45^th anniversary in 2021. Furthermore, he was a board member and treasurer of the Technical committee no 4 of the International Federation for Information Processing (IFIP), which managed matters concerning global health informatics. From this base, he arranged the international congress for medical informatics, Medinfo, 1974 in Stockholm. As medical informatics was considered an extremely important branch of informatics, a separate global federation was founded in 1986 originating from IFIP TC 4 on his initiative, the International Medical Informatics Association (IMIA).

For 30 years Hans continued as a medical doctor in ophthalmology one day a week, and the rest of the week, probably 6 days rather than 4, he was an engagement in medical informatician. This devotion brought him to Kuwait and South Africa, where his and Paul Hall’s system was implemented. He was also a board member of the German medical informatics society and lectured in Italy. This engagement brought him international acknowledgment with several awards. The Italian president awarded him the Italian Republic’s Order ‘For Merit’ III degree. He has also been awarded the IFIP silver core in 1986 and The IMIA Award of Excellence in 2010.

At the age of seventy, Hans retired from professional work but continued to contribute to the development of medical informatics with knowledge and inspiration.

Hans Peterson died on 27 January 2021. A great medical informatician has left us in deep missing. The memory of him will always be alive in many systems around the World, where his competence has contributed to the development. Our best way to honour his memory is to sedulously continue the development of medical informatics.