Two new 17-membered carbocyclic tetraenes, chejuenolides A and B (1 and 2), have been isolated from the EtOAc extract of the marine bacterium Hahella chejuensis by various chromatographic methods. The structures and relative configurations of 1 and 2 were mainly determined by analysis of the NMR spectroscopic data, and their absolute configurations were assigned by application of modified Mosher method.