This study reports the synthesis and in vitro biological properties of dendrimer-antibody conjugates. The polyamidoamine dendrimer platform was conjugated to fluorescein isothiocyanate as a means to analyze cell binding and internalization. Two different antibodies, 60bca and J591, which bind to CD14 and prostate-specific membrane antigen (PSMA), respectively, were used as model targeting molecules. The binding of the antibody-conjugated dendrimers to antigen-expressing cells was evaluated by flow cytometry, confocal microscopy, and a new two-photon-based optical fiber fluorescence detection system. The conjugates specifically bound to the antigen-expressing cells in a time- and dose-dependent fashion, with affinity similar to that of the free antibody. Confocal microscopic analysis suggested at least some cellular internalization of the dendrimer conjugate. Dendrimer-antibody conjugates are a suitable platform for targeted molecule delivery into antigen-expressing cells.