Because a rise in incidence of virus hepatitis observed in some years and showing an epidemic nature begins in one year and continues in the first quarter of the following year, it is recommended to register the incidence not from January to December, but from July to June of the next year in studies of some regularities of the epidemic process. Also, since in Baku a rise in incidence begins in July, it is suggested that planned gamma globulin prophylaxis be carried out not in September, but in early July. It has been established that children under 14 have virus hepatitis type A 10--24.4 times as frequently as adults.