The author’s observations of numerous cases of molting in the hypogean asellid Stenasellus virei Dollfus, 1897 appear to show that the phenomenon occurs in two steps. The loss of the anterior exuvium is separated from that of the posterior exuvium by a period of 8 to 16 days in adults from cavernicolous populations of Stenasellus virei in the Pyrenees and Cantabrian Alps. The intermolts last from 9 to 18 months for the same individuals. One must allow, for this species, a minimun life span of 10 years. Values of the same order of magnitude are anticipated for the two other Pyrenees species, Stenasellus breuili Racovitza, 1924 and Stenasellus buili Remy, 1949. These observations agree with those previously made on other cavernicolous peracarid crustaceans, such as Caecosphaeroma burgundum Dollfus and Niphargus virei Chevreux, by Daum (1954), Husson (1959) and Ginet (1960).