We describe the guidelines used and the clinical and epidemiological data of a varicella outbreak seen in our service. The index case was a male drug addict, seropositive for HIV, with disseminated varicella. A total of 40 health care workers were in contact with the patient. Of them, 37 were considered not to be susceptible of having the disease. The remaining three health care workers developed varicella, and one had been also in contact with other hospitalized patients during the exposure period. Serological test for varicella (FAMA) of all 20 exposed patients (all HIV positive) showed that only four were susceptible. Those were put on isolation and immunoglobulin against zoster-varicella (VZIG) was used. Only one developed varicella. We recommend: a) the index case has to bep put under strict isolation precautions or discharged; b) acyclovir should be given to all immunosuppressed patients; c) immunoglobulin (VZIG) should be used in immunosuppressed patients susceptible to varicella and exposed to index case, and d) live, attenuated vaccine should be used in non immunosuppressed susceptible patients.