Immunoassay methods and apparatus are provided which utilize flow cytometry, coated latex microspheres, and fluorochrome labeled antibodies, to simultaneously detect the presence and amount of one or more analytes in a sample. By combining FALS and fluorescence, it is practical to use beads of several different sizes, colors or shapes, each bead coated with a different analyte, for the simultaneous detection of one or more analytes and of cell components such as platelets in a sample.