The surface tension of three binary liquid mixtures of NO with Kr, CH4, and C2H4 has been determined as a function of composition in the temperature range 102.0 to 119.0 K. These measurements are a contribution to the study of binary liquid mixtures in which one component is unassociated while the molecules of the other can associate between themselves. Nitric oxide is the simplest molecule capable of forming dimers, but not larger aggregates. This results in the surface tension of liquid nitric oxide having a strong temperature dependence : when the temperature increases the degree of dimerization decreases, contributing to a larger decrease of the surface tension, The surface tension of NO mixtures shows strong deviations from ideality. The mixtures containing Kr and CH4 exhibit negative deviations, while for the NO + C2H4 system the surface tension shows a complex dependence on the composition, This strong departure from ideality had already been found for the bulk properties of these three systems, The surface tension of the CH4 + Kr system, already well characterized in the literature, was also measured to test our equipment.