A case of unilateral mydriasis secondary to septoplasty under local anaesthesia. Septoplasty is a procedure performed to correct deformities of the nasal septum. Serious complications associated with septoplasty include orbital complications. Here, we present a 26-year-old male patient who developed unilateral mydriasis while undergoing septoplasty under local anaesthesia. The mydriasis resolved spontaneously in an hour without any sequel. In the present study, we emphasise the orbital complications that can be observed during septoplasty.