Chickenpox (varicella) is a highly infectious disease caused by the varicella-zoster virus (VZV). Primary infection results in varicella, manifesting as a generalized, pruritic, vesicular rash typically consisting of 250 to 500 lesions in varying stages of development and other systemic symptoms (mild fever, fatigue). Reactivation results in herpes zoster, characterized by grouped vesicular lesions in the distribution of the sensory dermatomes. Immunocompromised persons or pregnant women without a history of varicella disease or vaccination are at the highest risk for severe varicella disease. Varicella is one of the last epidemically occurring exanthematic diseases of infancy in the countries without routine vaccination against varicella. The incidence of 327.7/100 000 inhabitants was reported in the Slovak Republic in 2009.The diseases can be prevented by vaccination.