Amplification of X sequences (131 bp) and Y sequences (172 bp) in males and X sequences in females was satisfactory in almost all samples. Of 22 samples (5 blood, 12 dental pulp, and 5 tooth hard tissue), a false positive fragment was detected at 172 bp among female samples as a result of silver staining. These bands were not amplified by the dual PCR method and were different from the Y-specific band. Subsequent restriction enzyme digestion of bands resulted in different patterns from the typical Y-specific band. Further, in five male samples of hard tooth tissue specimens, a Y-specific band was detected as a weak band; in two of the five samples, this weak specific band was not amplified by dual PCR despite the male origin of the samples. Results showed that the PCR amplification method is useful in sex determination but that dual PCR and restriction analysis should be used together in practical applications. 24 references, 2 tables, and 6 figures