The presentation of Hodgkin's disease and acute infectious mononucleosis (glandular fever) due to Epstein-Barr virus, have similar seasonal features with the peak incidence around March. The extent of seasonal variation is also similar. Seasonality of Hodgkin's disease is most obvious and also significant in adult age groups below the age of 40. Amongst those over 40 years, seasonality was no longer present in the 40-59 but returned over age 60. Seasonal similarity does not prove a relationship. However two speculations are made on possible mechanisms. Firstly glandular fever may accelerate presentation in young adults, destined to present with HD. Secondly the Epstein-Barr virus may have an inherent seasonal behaviour whether causing acute infectious mononucleosis or when latent and playing a role in the aetiology of Hodgkin's disease.