Grand canonical Monte Carlo (GCMC) simulations of ethylene physisorption on the basal plane of graphite are reported. The calculated isotherms are compared with experimental results at several temperatures. The maximum surface coverage studied is close to one monolayer. The ethylene molecules are described as six Lennard-Jones interaction sites. Three models are compared to introduce the quadrupolar interactions. The isosteric heat of adsorption at zero coverage is also calculated, and the obtained value is compared with experimental results obtained by other authors.