Kogiso T, et al. - Since the incidence of acute hepatitis A [AH (A)] is decreasing due to improvements in hygiene, however, cases of sporadic severe hepatitis are still reported, researchers evaluated the epidemiology of AH (A) in Japan. Participants in the study were 126 AH (A) patients (96 men [76%], median age 39 [range, 19–66] years). Data reported that the incidence of AH (A) in 1990, 1999, and 2018 showed peaks. HAV was transmitted, respectively, by raw oysters, overseas travel, and sexual contact before and after 2001. The symptom frequencies were, respectively, loss of appetite, fever, and diarrhea. The data presented in this work showed time to normalization of the bilirubin level ≥ 30 days was related to older age and a diagnosis of AH (A) after 2001. Recently, outbreaks and severe AH (A) cases have been reported due to sexual transmission in this hospital-based retrospective study. Findings suggested that their sexual behavior and other sexual infections need to be examined.