At 5$^{circ}C$ incubation of the brooded eggs of the snow crab, Chionoecetes opilio lasted for 297 days; freshly hatched prezoea molted to become the first zoea in one hour. Length (from the tip of the rostral spines to the tip of the dorsal spines) of the first and second zoeae measured 4.8 and 6.4mm, respectively. Experimental rearing of the larvae at 5, 10, 15 and 2$0^{circ}C$ indicated that the upper limit of thermal tolerance is 15$^{circ}C$, as all the reared larvae succumbed at 2$0^{circ}C$. Intermolt period from the first the first zoea to the second was 57, 32 and 23 days at 5, 10 and 15$^{circ}C$, respectively and that of the second zoea was 52, 29 and 90 days, respectively. Largest number of larvae survived at 1$0^{circ}C$.