Four known butenolides were isolated from the ethyl acetate extracts of the culture broth of the marine-derived bacterium, Streptoverticillium luteoverticillatum, by bioassay-guided fractionation. The structures were identified on the basis of spectral data. The absolute configuration of compound (1) was determined by CD spectrum for the first time. Compounds 1-4 showed in vitro cytotoxicity against the murine lymphoma P388 and human leukemia K562 cell lines. This is the first report on the isolation of butenolides from the marine bacterium, Streptoverticillium luteoverticillatum, and their cytotoxic activities.