Two 3 β - methoxy secosteroids, named jereisterol A and B were isolated from the pacificsponge Jereicopsis graphidiophora Lévi & Lévi. Their structures, which combine rare 3 β-methoxy and seco features, were determined as (24 R) 24-methyl-3β-methoxy-8α,9α-oxido-8,9-secocholesta-7,9(11)-diene (1) and (24R) 24-methyl-3β-methoxy-8,14-secocholesta-8,14-dione (2).