The possibility of synergistic effects in binary gaseous mixtures was investigated for the differential and integral adiabatic Joule-Thomson effects. The main purpose was to find the conditions for a synergistic effect in the integral Joule-Thomson effect, using the van der Waals, Redlich-Kwong, Soave, and Peng-Robinson equations of state and the variation of the excess molar enthalpy with pressure. Synergism was found to be possible in very few systems. The conditions for the presence of a synergistic effect were found using the plane of the reduced isothermal Joule-Thomson effect over all pressure ranges.