Respiratory syncytial virus (RSV) and rotavirus infections are long-standing infectious diseases that affect children worldwide. RSV and rotavirus were first discovered in clinical specimens in 1955 and 1973, respectively. From their discovery to the present day, significant progress has been made in understanding these two infections. The introduction of a simple and rapid antigen diagnostic test into clinical settings in the 1990s offered new insight into the clinical characteristics and epidemiology of these infections. Regarding therapeutics, symptomatic treatments have remained the mainstay; however, prophylactic humanized anti-RSV monoclonal antibodies have been developed and advances in structural biology may allow for more effective human anti-RSV monoclonal antibodies and novel RSV vaccines to be developed soon. For rotavirus, two vaccines have been licensed and broadly applied over the past 10 years, which have been successful clinically and have changed the epidemiology of rotavirus infections in Japan.