- McLeod Family Papers, 1873-1990 (bulk 1900-1965)787
- McLeod Plantation Cemetery Collection1
- Medical College Expansion Program Lantern Slides,1
- Medical College Expansion Program Lantern Slides, 1954-1974201
- Medical Society of South Carolina Collection1
- Medical Society of South Carolina Digital Collections80
- Medical University of South Carolina Board of Trustees Collection, 1824-201277
- Medical University of South Carolina University Bulletins, 1878-2002182
- Medical University of South Carolina Yearbooks26
- Mercantile Agency Reference Book of South Carolina175
- Metchicas and Kehayas Family Letters30
- Micajah Adolphus Clark Journals, 1847-18572
- Middleton Family Art Work, 1803-18671
- Middleton Family Papers, 1736-19291
- Middleton Papers, 1775-181512
- Midlands Memories999
- Midlands Memories
9
- Midlands Memories 3
- Millbrook account, n.d.1
- Millicent E. Brown Papers, 1949 - 200377