The Langmuir-Blodgett (LB) film formation behavior of the endohedral metallofullerene Dy@C82 was studied at the air/water and Ar/water interfaces. The LB film constructed at the Ar/water interface (2-4 layers) was found to be thinner and more uniform than at the air/water interface (4-6 layers). Particulate aggregates were observed in the LB films, which contrasts the extended wire networks formed by direct evaporation of the metallofullerene solution on a quartz plate. The UV-Vis absorption peaks are blue-shifted for the LB film deposited in air, which is attributed to the partial oxidation of the metallofullerene balls. They are red-shifted, however, for the LB film at the Ar/water interface presumably due to the interaction between the pristine metallofullerenes.