in 1999, a case of diphtheria in a 32-year-old woman was reported. the patient developed a sore throat immediately after participating of a five-day meeting with european workers in rio de janeiro. her history included complete pediatric immunization (dtp) and three doses of adult formulation tetanus and diphtheria toxoid (dt) two years earlier. clinical diagnosis of diphtheria was not made until microbiologic examination of specimens confirmed toxigenicity of corynebacterium diphtheriae var. gravis, a biotype currently found circulating within europe where diphtheria remains epidemic. this case reinforces the potential susceptibility of brazilian adults to epidemic diphtheria in the vaccine era.