Several examples of transparent blends of a multiblock copolymer and a foreign homopolymer which is immiscible with each of the copolymer constituent blocks taken separately are described (homopolymers : polystyrene, polymethylmethacrylate and polyvinylchloride; multiblock copolymers : polysulphone/polybutadiene, polycarbonate/polydimethylsiloxane, polysulphone/polydimethylsiloxane and polytetramethylenoxide/polybutadiene). The blends were prepared by casting films from solutions of the components in a common solvent (tetrahydrofurane or chloroform). The critical content of multiblock copolymer in the homopolymer matrix for transparency was found to be about 5 wt% but may be as much as 20 wt%. It was found that the physical basis of the blend transparency is not thermodynamic compatibility of the components but separation of the multiblock copolymer phase in the homopolymer matrix in the form of small-sized particles (up to 100 nm in diameter). These transparent blends are microheterogeneous systems and they are also similar in the sense that the constituent blocks were found to segregate in the block copolymer microphases.