In the course of our ongoing research for antimicrobial agents, we isolated five new compounds, three 24-membered macrolactones, macrolactins X-Z (1-3) and two hydroxy unsaturated fatty acids, linieodolides A (5) and B (6), together with a known metabolite, macrolactinic acid (4), from the culture broth of a marine Bacillus sp. The structures of these metabolites were determined on the basis of their spectroscopic data interpretation. Their absolute configurations were addressed by modified Mosher's method and literature data review. Compounds 1-6 showed moderate to potent inhibitory activities (8∼128 μg ml(-1)) against selected pathogenic microorganisms.