Today, temporary henna tattoos drawn on the skin are very fashionable and have become more and more popular. At the same time, allergic reactions following these tattoos has increased worldwide. Actually, henna has a very low allergic potential. In most cases, allergic reactions are caused by the mixtures used by the so-called "artists" which contain not only natural henna but also many chemical coloring agents such as diaminotoluenes and diaminobenzenes. The long duration of skin contact, the high concentrations of sensitizing materials, and the lack of a neutralizing agent dramatically increases the risk of skin sensitization. We summarized 31 of our own cases with allergic contact dermatitis due to temporary henna tattoos and outlined the main characteristics for this peculiar contact dermatitis.