The vapour pressures of (water + pyridine, or 2-methylpyridine, or 3-ethylpyridine, or 2,4,6-trimethylpyridine) have been measured in a very narrow range of concentration at T = 353.15 K using the ebulliometric method. The saturated vapour pressures of the pure substances are also given. Based on the experimental results, the activity coefficients at infinite dilution have been calculated.