A series of N-substituted benzyl-6 (or 7)-ethyl-2,3,4,9-tetrahydrofuro[2,3-b]luinolin-3,4-diones were synthesized. They were evaluated for anti-allergic and anti-inflammatory activities by inhibition of mast cell degranulation, neutrophil degranulation, and superoxide formation in neutrophils. Among them, N-ofluorobenzyJ-6-ethyl-2,3,4,9-tetrahydrofuro[2,3-b] quinolin-3,4-dione (39) significantly inhibited fMLP-induced neutrophil degranulation at high concentrations (30 μM). The structure-activity relationships of these compounds indicated that ethyl substituted derivatives displayed stronger inhibitory activity against the release of β-glucuronidase during fMLP-induced neutrophil degranulation compared to 7-ethyl substituted derivatives.