Abstract Colloidal gold particles coated with goat anti-mouse immunoglobulin antibodies were used to analyse surface antigens on various cell types by flow cytometry. The gold-labeled cells showed an increasing signal amplification in the 90° light scatter with increasing wavelength of the incident laser light, reaching a more than 10-fold amplification at 632.8 nm. This wavelength was provided by a 0.5 mW helium-neon laser. The magnitude of the signal amplification due to the gold label as well as the specificity of the label was sufficient for quantitative discrimination between positive and negative cells. Cell viability was not affected by the gold label. Mouse spleen cells were labeled with various combinations of FITC- and gold-conjugated antibodies. It was found that the gold and fluorescent labels did not interfere with each other. Colloidal gold may thus be used as an additional label for multiparameter cell analysis and sorting. Biparametric cell analysis/sorting of surface antigen-labeled cells (label versus low-angle scatter) becomes possible even with a low energy helium-neon laser.