Liquid–liquid cloud point diagrams of solutions of nearly monodisperse samples of polystyrene (PS), and binary mixtures of nearly monodisperse PS’s, both in methylcyclohexane (MCH), were determined for several polymer molecular weights ( M w) at 0.1 MPa. The bimodal mixtures (PS[ M w(1), ρ(1)] + PS[ M w(2), ρ(2)], M w(1)=90×10 3 g/mol, M w(2)=13×10 3 g/mol, 5.78 × 10 3 g/mol, and 2.2 × 10 3 g/mol, ρ=1.06) were prepared constraining 〈 M w〉=38.6×10 3 g/mol, ρ= M w/ M n is the polydispersity index. In each case the cloud point curves (CPC’s) for the bimodal mixtures are strongly skewed, lying well above CPC for 〈 M w〉 when φ< φ CRITICAL, and below CPC for 〈 M w〉 when φ> φ CRITICAL; φ is volume fraction polymer in the polymer/solvent mixture. The experimental results are discussed in the context of empirical and mean-field representations.