Ten of 18 children in a highly inbred Arab kindred suffered from either ataxia telangiectasia (AT) or a variant syndrome consisting of ataxia, microcephaly, and congenital cataract (AMC). Four of the nine afflicted children were treated in our unit when they developed lymphomas (both Hodgkin's and non-Hodgkin's including Burkitt's). They were given chemotherapy (either standard COMP or low-dose ABV/CVPP). The children with non-Hodgkin's lymphomas died of sepsis after receiving full-dose COMP. Low-dose ABV/CVPP brought about a 20-month remission in one child with nodular sclerosing Hodgkin's lymphoma and both AT and AMC, but she developed a preleukemic syndrome and her parents refused further treatment; she too died. A fourth child, also with nodular sclerosing Hodgkin's lymphoma, is currently in complete remission after ABV/CVPP. Treatment of lymphomas in patients with AT is extraordinarily difficult and has potential side effects so grave as to necessitate careful monitoring and individualized protocols.