Aims: The aim of this study was to explore Finnish physicians' perceptions of sickness absence (SA) certification. Methods: A questionnaire was sent to 50% of the physicians in Finland who provide care to working-age patients in a clinical practice setting. Of the 8867 physicians, 3089 responded. Physicians handling SA certification patients at least a few times per month were included (n = 2472). Results: At least a few times per month, 61% of all physicians perceived SA issues as problematic, 60% had experienced a lack of time in dealing with SA matters, 36% had disagreed with a patient on SA certification, and 36% had met a patient who wanted a SA certificate for reasons other than a disease or injury. Physicians were least worried about patients filing complaints (4%), exhibiting threatening behaviour (2%), or switching physicians for SA certification reasons (1%). A total of 60% of physicians had prescribed SA for a longer period than necessary because of long waiting times for further care/measures. Non-specialized physicians, general practitioners, and psychiatrists experienced problems more frequently than surgeons and occupational health physicians. Over 50% of the respondents had a fairly large or very large need to deepen their knowledge of social insurance matters. The need for national guidelines for all or some diseases was reported by 80% of the respondents. Conclusions: Many physicians perceive SA tasks as problematic and are unable to dedicate enough time to them. Shortcomings in physicians' sickness certification know-how, as well as obstacles in the healthcare and rehabilitation system, prolong the SA process. Attitudes towards the adoption of national guidelines on the duration of SA were positive.