We report the first described case of a first rib fracture secondary to pertussis infection. An 11-year-old boy presented with sudden onset of severe right-sided pleuritic chest pain on a background of a 6 week history of a coughing illness and considerable weight loss. Pertussis was clinically suspected and proven on serology. A cause for the severe pain was initially difficult to confirm, causing some concern regarding possible underlying pathology, but was later demonstrated to be due to a first rib fracture. The anatomy of the first rib, and the biomechanical forces placed upon it that are exacerbated during a coughing illness are described.