A flow-injection polymer analysis (FIPA) method for the dilute solution characterization of unsaturated styrenic block copolymers was developed. The method is rapid, works with both butadiene and isoprene comonomers, and covers a range of 0 -100% styrene content in the polymer. Solutions of the polymer were introduced into a flowing mobile phase and monitored by an array of three close-coupled detectors: a right-angle laser light-scattering unit, a differential refractive index detector (DRI), and a differential pressure viscometer. In addition, a separate, dual-detector instrument was set up specifically to evaluate the styrene content by the FIPA method. In that case, the detectors were a DRI and an ultraviolet detector. Within an analysis time of a few minutes, information on molecular weight, molecular size, and comonomer composition could be obtained directly. The data were compared to those obtained from a preexisting gel permeation chromatography analysis method.