Two novel isocoumarins, erigeronone C (1) and D (2), were isolated from the ethanol extract of the whole plant of Erigeron breviscapus (Vant.) Hand.-Mazz (Compositae).  Their structures were respectively elucidated as 8, 9-dihydroxypyrano 3, 2-c isochromen-4, 6-dione (1) and 4, 7-dihydroxy-3-(3-hydroxy-4-oxo- 4H-pyran-2-yl)-1H-isochromen-1-one (2) on the basis of spectral analyses.  Both structures of 1 and 2 possess a γ-pyrone moiety and that is rare in natural products.