A predictive version of the UNIQUAC model is proposed for the description of the nonideality of paraffinic solid solutions. With this model, and using only pure component properties, is possible to adequately predict the phase behavior of complex hydrocarbon mixtures. Both liquid and solid phase compositions as well as the fraction of crystals in a partly frozen solution show a good agreement with experimental data from different authors. Unlike previous models, predictive UNIQUAC can deal with the multiple solid phases forming in a paraffinic mixture overcoming one of the main Limitations of hydrocarbon SLE modeling.