BackgroundTetanus is a life-threatening disease caused by tetanus neurotoxin (TeNT) produced by Clostridium tetani. Early symptoms of tetanus are trismus and muscle stiffness, both caused by spasticity. TeNT mainly exerts its effect by impairment of inhibitory neurons in the spine and brainstem, resulting in the hyperactivity of motor neurons, which causes spasticity and muscle spasms. Apnea is not a symptom that is predicted to occur in the early stages. Case ReportWe present a rare case of severe tetanus with an early manifestation of apnea but without trismus. We believe that apnea was caused by spasms of the intercostal muscles and its early manifestation was due to a high load of TeNT, considering that the speed of disease progression is related to disease severity. We hypothesize that the absence of trismus was also due to a high load of TeNT, exerting toxic effect at the neuromuscular junction and causing flaccid paralysis of the massetersWhy Should an Emergency Physician Be Aware of This?:Since there is no diagnostic laboratory test for tetanus, emergency physicians must be well aware of symptoms that may or may not appear in tetanus. Tetanus should be considered as a differential diagnosis for patients arriving at the emergency department with apnea as an early symptom. The absence of trismus should not rule out the possibility of tetanus.