Enthalpies of mixing for the binaries m-xylene + pyridine and its methyl derivatives have been measured at 298.15 K. The pyridine bases used for the measurements were pyridine, 2-, 3-, and 4-methylpyridine, 2,4-, and 2,6-dimethylpyridine, and 2,4,6-trimethylpyridine. The Prigogine-Flory-Patterson (PFP) model has been applied to describe the experimental results.