The interaction of silver trimer with ethylene molecule is investigated within the density functional framework using the Becke exchange and Perdew-Wang (91) correlation functionals. Structural forms and electronic properties (binding energy and ionization potential) of the cluster-molecule complex are determined. Ag-3-C2H4 forms two isomers. In agreement with the experimental results, the computed ionization potential of the more stable isomer is lower than that of the bare Ag-3 cluster.