Sorption isotherms of nonionic dyes with two amino groups (one anthraquinone dye and two azo dyes) on various polymers from water were measured at 40-90 degrees C (Nylon-6 and cellulose film) and at 95 degrees C (polyester microfiber). The isotherms were curved, convex to upward, in the range of low dye concentration C-s in water and almost linear in the range of medium to saturated C-s. The isotherms measured at low temperature (40 degrees C for cellulose, 40-60 degrees C for Nylon-6, and at 95 degrees C for polyester) were satisfactorily described by considering three concurrent modes of sorption. They are Nernst type partitioning and bimodal Langmuir sorption (sorption by the higher affinity sites with a small saturation value and that by the lower affinity sites with a large saturation value). However, for the sorption of the anthraquinone dye and one azo dye by Nylon-6 film at high temperature (80-90 degrees C), the amount of dye sorbed by the high affinity site decreased to negligibly small. Accordingly, the isotherms were expressed well by simple dual-sorption model.