In a group of 612 consecutive patients undergoing routine patch tests for suspected allergic contact dermatitis, more than four-fifths of the 364 women had had their ears pierced, over half gave a history of cutaneous reactions to metallic jewelery and almost one-third were sensitive to nickel. The increase in the frequency of nickel sensitivity in women with pierced ears compared to those with unpierced ears was highly significant (P less than 0.001). In men, nickel sensitivity was much less frequent; occupational factors were often implicated and few cases were related to ear piercing. Jewelery dermatitis was more frequent in atopic than non-atopic women but atopy did not appear to influence the propensity for developing nickel sensitivity in either sex. Ear piercing seems to induce nickel allergy which may result in lifelong morbidity and difficulty in employment. Jewelery suppliers should be encouraged to provide nickel-free earrings to reduce the frequency of this apparently avoidable problem.