丙型肝炎或称C型肝炎（Hepatitis C）是一种由C型肝炎病毒引起的体液传染性疾病，主要影响肝脏。初期的症状轻微，甚至没有症状。偶尔会有发烧、小便黄赤、腹痛及黄疸等症状。约有75%至85%的初患病者，其病毒会持续在肝脏中，早期的慢性丙型肝炎一般没有症状，但许多年后会变成肝病，偶尔也会变成肝硬化。有些有肝硬化的患者会有其他的并发症，例如肝功能衰竭、肝细胞癌、食道静脉曲张或胃底静脉曲张。

该病的传播大多借由共用针头、消毒不完全的医疗设备、在进行健康照护工作时的针扎伤害还有输血造成。现在有了血液筛检作业后，经由输血而感染的病例已小于两百万分之一。还有另一种传播方式是母亲在生产时给婴孩。一般日常生活的接触是不具传染性的。C型肝炎是已知五种肝炎病毒的其中一种：A型、B型、C型、D型、E型。诊断方法是检测血液中是否存在血清抗体或是病毒的RNA。只要是暴露在危险因子下的民众，都会建议进行筛检。

Hepatitis C is an infectious disease caused by the hepatitis C virus (HCV) that primarily affects the liver. During the initial infection people often have mild or no symptoms. Occasionally a fever, dark urine, abdominal pain, and yellow tinged skin occurs. The virus persists in the liver in about 75% to 85% of those initially infected. Early on chronic infection typically has no symptoms. Over many years however, it often leads to liver disease and occasionally cirrhosis. In some cases, those with cirrhosis will develop complications such as liver failure, liver cancer, or esophageal and gastric varices.