Sickness absence is a common ''prescription'' in health care in many Western countries. Despite the significance of sick-listing for the life situation of patients, physicians have limited training in how to handle sickness-certification cases and the research about sickness-certification practices is scarce. Gain knowledge on physicians' learning regarding management of sickness certification of patients in formal, informal, and non-formal learning situations, respectively, and possible changes in this from 2004 to 2008. Data from two comprehensive questionnaires to physicians in Sweden about their sickness-certification practice in 2004 (n = 7665) and 2008 (n = 36,898); response rates: 71% and 61%, respectively. Answers from all the physicians ≤64 years old and who had sickness certification tasks (n = 4019 and n = 14,210) were analysed. ratings of importance of different types of learning situations for their sickness-certification competence. Few physicians stated that formal learning situations had contributed to a large or fairly large extent to their competence in sickness certification, e.g. undergraduate studies had done that for 17%, internship for 37%, and resident training for 46%, respectively. Contacts with colleagues had been helpful for 65%. One-third was helped by training arranged by social insurance offices. There was a significant increase between 2004 and 2008 in all items related to formal and non-formal learning situations, while there were no changes regarding informal learning situations. This study of all physicians in Sweden shows that physicians primarily attain competence in sickness certification in their daily clinical practice; through contacts with colleagues and patients.