In October 2011, a child who had arrived in Sweden from Somalia presented with atypical tonsillitis, was treated with penicillin and the symptoms resolved. A throat swab was positive for toxigenic Corynebacterium diphtheriae. The child's family were then vaccinated with diphtheria, tetanus and pertussis vaccine and screened for C. diphtheriae. No secondary cases were found. A high level of adherence to childhood vaccination programmes is an effective way to protect populations against diphtheria.