In this work the Kirkwood-Buff integrals, G(ij), have been determined in the whole concentration range for binary mixtures containing aliphatic alcohol and heptane, where the alcohols are ethanol, 1-propanol, 2-propanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 1-butanol, 1-pentanol, and 1-octanol, and for the ternary mixture heptane + ethanol + propanol at the temperature 313.15 K. For binary mixtures containing the alcohols ethanol, 1-propanol, 2-propanol, 2-methyl-1-propanol, and 1-octanol the temperature dependence of these quantities has been investigated too. Obtained values of G(if) integrals were interpreted (as products cG(11)) in terms of the values of the association constant of the alcohol and differences in molecular sizes between the alcohol and the hydrocarbon molecules. It has been shown that for binary mixtures the plot of cG(11) (where c = N/V is alcohol concentration) as a function of alcohol mole fraction has two characteristic maxima : at approximately x(1) = 0.1 and x(1) = 0.45. The concentration dependence of the local alcohol mole fraction, x(11), has two maxima too, at, approximately, the same places (i.e. about 0.1 and 0.45 mole fraction of alcohol). It has been found that, for binary mixtures, if the alcohol association constant increase, then the maximum at x(1) = 0.45 becomes more distinct, and simultaneously the relative height of the maximum at x(1) = 0.1 is reduced. The same effect may be observed if the difference in molecular sizes between the alcohol and the hydrocarbon molecules increases. For the ternary mixture heptane + ethanol + propanol the linear coefficients of preferential solvation have been investigated. From those results it appears that preferential solvation of ethanol by ethanol is nearly the same as that of propanol by ethanol, and preferential solvation of ethanol by propanol is nearly the same as that of propanol by propanol. This indicates that propanol and ethanol mix in a nearly random manner in the whole concentration range of the ternary mixture.