Skulls were sectioned both sagittally and transversely to measure the petrous portion completely. Nine dimensions on both left and right petrous portions were analyzed by discriminant analysis to determine which combination of variables offered the best discriminating power for determining sex. All combinations of variables were attempted to provide the best possible accuracy of sex determination. Results showed that the petrous portion of the temporal bone of the skull frequently survived circumstances that caused skeletal fragmentation and that up to 74 percent accuracy was obtained in determining sex from the petrous portion. The authors conclude that sex determination from the petrous portion is a valuable tool for forensic anthropologists. 11 references, 3 tables, and 1 figure