Abstract The Taiwanese hagfish Paramyxine cheni (Myxidae) is believed as a primitive species in the Eptatretinae and it distributes on the west south coast of Taiwan. Hagfishes are noteworthy to study from an evolutionary standpoint because they represent the oldest extant clade among the craniates. A better understanding of their reproductive states may thus reveal information for fisheries management. This research presents data on size, weight, GSI (Gonadosomatic Index), HSI ( Hepatosomatic index) and reproductive states for specimens collected at a study site (22¢X22¡¦43¡¨N, 120¢X14¡¦92¡¨E) near Tong-kung, Southern Taiwan. Specimens were collected once a months from December 2002 through November 2003 for body weight, body length, gonad weight, liver weight and liver lipid content. GSI, show that the P.cheni had a seasonal reproduction period in April and May. HSI data also show a positive correlation with GSI. The sex ratio among the female, male and sex undeterminated individuals was 0.51¡G0.20¡G0.29. The maximum body length was 55.9cm, and smallest body length was 9.5cm. I define the full maturity as appearance of the mushroom-like structure at the tips of the egg. P.cheni matured around 40cm. Gonad developed at 18.5cm body length, when minute eggs observable by naked eye are present. Lipids distribution in liver was significantly different in female before and after the reproduction period; lipid cells were more condense in the former period. Color of liver difference between the male and female P.cheni; male¡¦s liver was more reddish. Therefore, before sex differentiation, I can identify the sex of an individual by the color of its liver.