Many terpenoid quinones and phenols from marine sponges have been shown to exhibit interesting biological activities. We have also reported the isolation and structural elucidation of three novel antineoplastic sesquiterpenoids, metachromins A, B, and C, from the Okinawan marine sponge Hippospongia metachromia. In our continuing studies on bioactive metabolites from marine organisms, we further examined extracts of the same sponge H. metachromia to obtain five new cytotoxic sesquiterpenoids, metachromins D-H (1-5), together with known related compounds metachromins A (6) and B (7). In this paper we describe the isolation and structural elucidation of 1-5.