The transcription factors, DMRT1 and FOXL2, play a role in fish sex differentiation of the bipotential precursor into the male and female pathway, respectively. In order to provide the molecular background for understanding hormonal regulation in sexual determination and differentiation in the red-spotted grouper, Epinephelus akaara, one of commercially important epinephelines, and is often used to study protogynous sex change. First, we amplified the partial sequence of two genes (DMRT1 and FOXL2) from the gonad of red-spotted grouper. Also, we surveyed the tissue-specific and sex-specific expression pattern of each genes by RT-PCR. The effects of 17α-methyltestosterone (MT) in the sexually immature gonad of red-spotted grouper were investigated by Real-time quantitative RT-PCR. Fish were treated with MT-dipping method from around 70 days after hatching (DAH) for two month. DMRT1 and FOXL2 cDNA flagments consist of 489 and 836 base pairs (bp) and encodes a protein of 162 and 278 amino acids, respectively. RT-PCR revealed that DMRT1 mRNA was expressed higher level in the testis. Foxl2 was expressed extensively in the neural and peripheral tissues with its highest level in the ovary, indicating a potential role for Foxl2 in the brain-pituitary-gonad axis. Real-time quantitative RT-PCR analyses showed that DMRT1 mRNA expression was upregulated in the MT-treated fish. These results suggest that the sex inversion of red-spotted grouper by MT might be due to the suppression of FOXL2 gene expression, and resulting in the induction of the 11-KT secretion.