Traumatic carotid artery dissection, if not diagnosed and treated early, is a serious problem with permanent neurological deficit and a high mortality rate of up to 40%. We present a case with delayed diagnosis of traumatic carotid artery dissection in a 21-year-old female. While there were no ischemic infarct findings on the admission cerebral computerized tomography (CT), such findings were observed on two cerebral CTs taken because of the left hemiplegia noticed seven days later when the patient regained consciousness. The patient was referred to our emergency service, and definitive diagnosis was achieved with arterial Doppler ultrasonography, cerebral magnetic resonance imaging (MRI), diffusion MRI, and MR angiography. We did not consider invasive treatment since the neurological damage was permanent and dissection grade was IV according to angiography findings. The case was discharged within a week and physiotherapy was advised. Despite the advances in diagnostic methods, diagnosis of traumatic carotid artery dissection is still missed or delayed, as in the case presented here. Early diagnosis can ameliorate permanent neurological damage or even prevent it. However, the vital factors for early diagnosis are the obtained anamnesis leading to appropriate radiological examinations, detailed physical examination and high clinical suspicion.