A Bachelor of Medicine, Bachelor of Surgery (Latin: Medicinae Baccalaureus, Baccalaureus Chirurgiae; abbreviated most commonly MBBS, but also BMBS, MB ChB, MB BCh and MB BChir) is an undergraduate medical degree awarded by medical schools in countries that follow the tradition of the United Kingdom. The historical degree nomenclature states that they are two separate undergraduate degrees. In practice, however, they are usually combined as one and conferred together, and may also be awarded at graduate-level medical schools. It usually takes five to six years to complete this degree.

A Bachelor of Medicine (MB, also BM, and BMed) is the primary medical degree awarded by medical schools in China and some medical schools in Australia and UK. It usually takes five years to complete. The word "Medicine" in this degree stands for the general term for the medicine subject rather than internal medicine. Hence, these medical graduates with an MB degree can still practice surgery.

The Bachelor of Medicine (or Bachelor of Medicine, Bachelor of Surgery) degree is considered MD-equivalent in US universities and medical institutions. In North America, the equivalent medical degree is awarded as Doctor of Medicine (MD) or Doctor of Osteopathic Medicine (DO)—the latter in the United States only.