This study looks to describe health care professionals’ knowledge regarding patient safety. A quantitative study using questionnaires was conducted in three multi-disciplinary hospitals in Western Lithuania. Data were collected in 2014 from physicians, nurses, and nurse assistants. The overall results indicated quite a low level of safety knowledge, especially in regard to knowledge concerning general patient safety. The health care professionals’ background factors such as their profession, education, the information about patient safety they were given during their vocational and continuing education, as well as their experience in their primary speciality seemed to be associated with several patient safety knowledge areas. Despite a wide variation in background factors, the knowledge level of respondents was generally found to be low. This requires that further research into health care professionals’ safety knowledge related to specific issues such as medication, infection, falls, and pressure sore prevention should be undertaken in Lithuania.