Four new compounds, including three new benzenoids, antrocamphin A (1), antrocamphin B (2), and 2,3,4,5-tetramethoxybenzoyl chloride (3), and a new 1,3-dioxolan-2-one derivative, antrodioxolanone (4), together with 13 known compounds have been isolated from the fruiting body of Antrodia camphorata. The structures of these new compounds were determined through spectral analyses including extensive 2D-NMR data. Among the isolates, antrocamphin A (1), antcin A (10), and antcin B (11) exhibited potent inhibition against fMLP-induced superoxide production with IC50 values less than 10 microM.