This document discusses the differences between case reports and case series in medical research. It notes that case reports typically include 1-2 cases while case series include 3-10 cases. Case series can be used to evaluate therapy safety and diagnostic accuracy without a control group. The document reviews criteria for case series, including clearly stating it is a case series in the title and methods section. It concludes that while both case reports and case series have limitations, they provide useful preliminary medical information if prepared adequately.