A recently presented model for compressed liquid densities of pure hydrocarbons (Aalto et al., 1995) is extended to mixtures, Mixing rules for the parameters V*, T-c,T-HBT omega(SRK) and P-c are given. A collection of mixing rules was compiled. 75 combinations of the mixing rules were evaluated using a compressed liquid density data base. The data base was collected during this work and it contained 4223 density data points for 49 binary and ternary hydrocarbon systems. The set of mixing rules recommended in this work gave an average absolute deviation (AAD) of 0.45%. The new model was compared to the original HBT correlation (Thomson et al., 1982), which gave an AAD of 0.57%. Based on the comparison done, it was found that the new model is more accurate than HBT and it can be used at higher temperatures near the vapor-liquid critical point. No binary interaction parameters are needed.