The molecular defect of congenital lipoid adrenal hyperplasia has been discovered to be in the transport of cholesterol into mitochondria due to defective regulatory protein called "Steroidogenic Acute Regulatory Protein (StAR)", while the enzyme P450scc itself is normal. This study with EcoRII restriction enzyme aimed at elucidating more conveniently the molecular defect in the StAR gene. The genomic DNAs were extracted from their peripheral blood. We amplified the exon 7, hot spot, of the StAR gene with 1 set of primers by Polymerase Chain Reaction (PCR). Subsequently, a PCR product corresponding to target sequence (~437 bps) from the patient and her father have been sequenced by automatic sequence analyzer. The PCR-RFLP (Restriction Fragment Length Polymorphism) analysis after restriction digestion with EcoRII restriction enzyme was also performed on 12% polyacrylamide gel electrophoresis. The mutation was identified in the exon 7 of the StAR gene, substituting C for T at codon 258, consequently replacing glutamine by stop codon. This mutation alters EcoRII restriction site. In addition, we obtained the good result of PCR-RFLP (Restriction Fragment Length Polymorphism) analysis on 12% polyacrylamide gel electrophoresis. Therefore, the PCR-RFLP (Restriction Fragment Length Polymorphism) analysis with EcoRII restriction enzyme can be easily utilized to screen carrier, diagnose the patient prenatally or postnatally.