Transtemporal approaches to the petrous apex and CP angle are standard procedures in the armamentarium of the neurotologist. In the majority of these cases, it is not possible to achieve a watertight suture closure of the dura following the procedure. Subsequently, cerebrospinal fluid leakage and potential meningitis are among the most troublesome complications for both patient and surgeon. Recent use of calcium phosphate cement (hydroxyapatite [HA]) has proved efficacious in animal studies and is now being used to close cranial defects in several medical centers, as part of an FDA-IDE study in human subjects. The use of this material is described in 11 neurotologic procedures. It is believed that hydroxyapatite cement (HAC) will become a standard tool in the management of cranial base and temporal bone defects following surgery.