치사율(致死率, 영어: case fatality rate, CFR, case fatality risk, case fatality ratio)은 어떤 병에 대해서 죽는 환자의 비율을 의미한다.
CFR in %=Number of deaths from diseaseNumber of confirmed cases of disease×100{\displaystyle {\text{CFR in }}{\%}={\frac {\text{Number of deaths from disease}}{\text{Number of confirmed cases of disease}}}\times 100}