We performed molecular dynamics computer simulations on DLPC and DPPC phospholipid monolayers at air/water and water/carbon tetrachloride interfaces. In our simulations the area per phospholipid molecule was 55 Angstrom(2) but the temperature was high enough, so that monolayers were in a liquid crystalline phase. The results of the simulations show that at this area per phospholipid molecule, carbon tetrachloride molecules do not penetrate extensively into the phospholipid tails. We also obtained information about the headgroup orientation, tail lengths, tail tilts, and S-CD order parameters for the tails. The S-CD order parameters indicate that phospholipids are more ordered at water/carbon tetrachloride interface than at water/air interface.