The novel oxazole peptide alkaloid, muscoride A (1), was isolated from terrestrial freshwater cyanobacterium Nostoc muscorum. The structure of muscoride A (1) was elucidated by extensive NMR measurements including phase-sensitive C-13 decoupled HMBC method. Muscoride A (1) is the first compound possessing N-(2-methyl-3-buten-2-yl)valine and two contiguous methyloxazoles.