Hepatitis B can be found in bodily fluids (sperm, blood, saliva, vaginal secretions, urine, mother's milk), so transmission is possible in unprotected vaginal and anal sexual intercourse and in oral-genital sex. Transmission is also possible through contact of infected saliva with the mucous membrane of a healthy person and through the common use of objects (toothbrush, cutlery, towel etc.). In addition, infection may occur with sharing syringes for injecting drugs. The infection often progresses without any clinical or laboratorial symptoms; in general, it resembles the symptoms listed under Hepatitis A.

The duration of the disease is longer than in Hepatitis A, and 5 to 10% of infected persons develop the chronic form, which may result in liver cirrhosis and liver cancer.