With advanced organ transplantation technology, steroid-induced osteonecrosis of the femoral head (ONF) is one of the most troublesome complications. Steroid sensitivity varies among individuals, and the involvement of polymorphism of various genes relating to steroid metabolism is suggested. The present study investigated the relation between single nucleotide polymorphism (SNP) on the DNA sequence of cytochrome p(450) and ONF development. The subjects were 80 renal transplant patients. Genome DNA was obtained from the peripheral blood, and SNP analyses for CYP3A4, CYP2D6, and CYP2C19 were conducted using various methods: direct sequencing, polymerase chain reaction restriction fragment length polymorphism, and DNA Chip. The relation between ONF development and SNP was statistically analyzed. It is useful if the generating risk judged according to SNPs to prevention of steroid-induced ONF is possible. This time, SNPs, which are clearly related to ONF, were not accepted, although the possibility that SNP related to steroid metabolism is involved in ONF development is important. We think that it is necessary to examine this area more closely.