Background: The condition of immunosuppression is a known condition that triggers reactivation of varicella zoster virus, to its manifestation as herpes zoster. Excessive exposure to ultraviolet is shown to decrease the immune system, even the effects can be systemic. Children often experience excessive UV exposure during play. Is excessive UV exposure a precursor to HZ in children? Case Report: We observed five cases of HZ in children aged 3-14 years; three of them are HZ ophthalmic, one HZ thoracic and one HZ brachialis. All had never received vaccine immunization and no history of intrauterine infection. Only one of them has suffered from varicella. There was no pathologic immunosuppression (HIV infection, organ transplant, immunosuppressant therapy, systemic disease) in these five children, but all children experienced intense UV exposure 3-5 days before the cutaneous lesions appeared. After treatment according to the HZ protocol, all recover without complications. Discussion: Various experimental models prove that UV exposure can suppress the immune system in some conditions: after vaccination, infection and provocation of allergic contact dermatitis in skin exposed directly or indirectly. This condition is in accordance with the state of immunosuppression that can trigger the reactivation of VVZ to HZ. The incidence of HZ is also reported to increase in the summer. All the patients we observed had intense UV exposure a few days before the emergence of HZ cutaneous lesions. Although only one patient clearly showed a history of varicella, subclinical VVZ infection may explain the reactivation of VVZ in all four cases. Based on the various evidence mentioned above, we conclude that intense UV exposure is very likely the main precipitating factor of HZ reactivation in children.