The incidence of temporomandibular joint (TMJ) dislocation in anaesthesia is poorly reported. Patients with a history of TMJ dislocation, algodysfunctional syndrome of the mandatory apparatus or retro mandibular facial dysmorphosis are predisposed to this complication. We report a case of TMJ dislocation, diagnosed just after a general anaesthesia for a vicious callus of a humeral palette fracture in a patient without risk factors for this dislocation. The patient had a normal pre-anaesthetic clinical exam. The clinical diagnosis is simple. Its reduction is an emergency which can be performed with or without sedation by any practitioner familiar with the Nelaton manoeuvre.