Abstract
Of a series of 28 patients with cytomegalovirus mononucleosis, 5 were treated with ampicillin and all these patients developed a rash 7–9 days after the start of this medication. Only 2 of the 23 patients not exposed to ampicillin had skin manifestations. Cytomegalovirus mononucleosis resembles infectious mononucleosis, not only haematologically, but also in inducing hypersensitivity to ampicillin.