A phenyl propanoid derivative, dillapionall(7) was found to be a antimicrobial principle of the stems of Foeniculum vuigare (Umbelliferae) with MIC values of 125, 250 and 125/ against Bacillus subtilis, Aspergillus niger and Cladosprium cladosporioides respectively. A coumarin derivative, scopoletin(2) was also isolated as marginally antimicrobial agent along with inactive compounds, dillapiol(3), bergapten(4), imperatorin(5) and psolaren(6) from this plant. The isolates 1-6 were not active against the Escherichia coli.