188 consecutive cases with basilar skull fractures(BSF) out of 2676 head injury patients who were treated in Chung-Ang Gil Hospital from July 1993 to June 1995, were analyzed. These fractures are difficult to diagnose by ordinary X-ray examinations, routine head computed tomography(CT) and are frequently inferred by clinical signs. Therefore, it's diagnosis is somtimes delayed or missed in initial assessment of trauma patients. They are different from cranial vault fractures in several aspects other than difficulties in the diagnosis. It involves more commonly the cranial nerves(CN), makes cerebrospinal fluid(CSF) fistulae and leads to central nervous system(CNS) infections if the CSF fistulae are not detected or treated early and properly. The authors reviewed the clinical features, radiological findings, rate of delayed diagnosis, complications and outcomes. The most common feature of BSF was otorrhea(64.4%) and followed by rhinorrhea(39.4%), raccoon eye(32.4%) and hemotympanum(24.5%). In only 6.4% of cases, the fracture lines were detected by ordinary skull radiographs and diagnosed as BSF. In contrast, the high resolution skull base CT confirmed the fractures in 62.2%. Clinical diagnoses were made in 14.9%. Commonly combined craniofacial lesions were cranial vault fractures(51.1%), intracranial hemorrhages(46.3%), and facial bone fractures(34.0%). Most of CSF leakages(89.7%) were noted within 24 hours after injury and most of the leakages (87.7%) had ceased by conservative management within 2 weeks, but 5.1% that did not respond to conservative treatment and lumbar CSF drainage, needed invasive operative repair. The incidence of meningitis was 3.2% and the prophylactic antibiotics had no benificial effect on lowering the infection rate. Facial nerve was the most frequently involved cranial nerve followed by vestibulo-cocchlear, oculomotor, and olfactory nerve in decreasing order of frequency. The onset of facial palsy was immediate in 31.8% and the remainder were delayed more than 24 hours after head injury. Of 188 patients, 21 cases(11.2%) were delayed in the diagnosis of BSF.