The attachment of ticks to human skin has been studied by scanning electron microscopy. Intact specimens of Ixodes ovatus and Ixodes persulcatus were examined, and we also studied the skin of two patients who had been bitten by these two species. In the first case, the remains of the tick were visible and a homogeneous cement-like substance was observed on the dorsal hypostome and in the dermis, suggesting that the tick attaches itself to the host skin by a secretion. In the second case, the apices of some denticles of the hypostome were chipped. Two months later, the skin which the tick had attacked was biopsied and yellowish-brown particles, probably derived from the denticles, were seen in foreign body giant cells in the dermis.