Viscosities, eta, of dimethylsulphoxide (DMSO), 1-butanol, 1-hexanol, 1-heptanol and those of their binary mixtures having DMSO as a common component have been experimentally measured at atmospheric pressure and 303.15 K. The experimental data have been used to calculate the deviation in viscosities, Delta ln eta, and excess Gibbs free energy of activation of viscous flow, Delta G(*E). The experimental viscosity deviation, Delta ln eta, have also been compared with theoretically calculated, Delta ln eta th, using Bloomfield-Dewan theory. These parameters were used to study the nature and extent of interaction between the component molecules in the present binary mixtures. Moreover, various semi-empirical correlations were used to estimate the viscosities of the present binary mixtures. The results are given in terms of average standard percentage deviations from experimentally measured one.