The present study reported an alternative way of sex-determining for scaleless worm goby Caragobius urolepis based on the regression relationship of some morphological parameters. A total of 328 samples were collected at the trawl nets in two coastal regions in Bac Lieu and Ca Mau from April to August 2022. After collection, the samples were transported to the laboratory in order to measure the total length (TL), body height (BD), head length (HL), the distance of eye (DE), and mouth width (MD) before surgery for accurate sex determination based on gonads. Regression analysis results of TL-BD (growth pattern A+ in females and I in males), TL-HL (growth pattern A+ in females and A- in males), and TL- MD (growth pattern A- in females and A+ in males) could be used to determine the sex of this fish. Moreover, TL-DE and TL-BD could be used to estimate when the samples were collected, e.g., in the dry or wet season, because DE and BD displayed A+ in the wet season but A- in the dry one. The findings could be used as an alternative way to determine fish sex and catching season for this species and others in the Mekong Delta.