Temporary 'black henna' tattoos, an increasingly popular body decoration in pediatric population, are associated with a growing incidence of adverse events. Black henna does not exist naturally, it is obtained from original henna after the addition of other compounds, among them paraphenilendiamine (PPD), which serves to darken the tattoo and allows greater precision to the design. PPD is known to be a strong sensitizer and increases the risk of allergic contact dermatitis. They may present as long lasting local reactions, and pigmentary sequels apart from problems with the future use of many products present in the daily life, as a result of sensitization by PPD. We report the case of an eleven-year old girl with an allergic contact dermatitis to black henna tattoo with a positive patch test to PPD, in order to warn against these types of temporary tattoos.