The conformation of the hydrocarbon chains of Aerosol OT or AOT, i.e. sodium bis (2-ethylhexyl)sulphosuccinate, was studied by laser Raman spectroscopy using its solution in isooctane containing different amounts of dissolved water in the presence of additives like cholesterol and anaesthetics like benzyl alcohol, diethylether, dichloromethane and chloroform. The measurements of the intensity ratio ( I r) of bands in the CH stretching region at 2910 cm −1 and 2870 cm −1 was found to be highly sensitive to chain conformation and was found to decrease with increase in the population of gauche conformers in the systems. Considerable bending and kinking was observed, as evident from the decrease in the intensity ratio I r, ( I 2910/ I 2870) in water/AOT/ isooctane microemulsion systems, and the trans-gauche equilibrium was found to depend on the amount of water dissolved in them. An increase in the density of microemulsion droplets was also found to shift the trans-gauche equilibrium more towards the gauche side. The presence of cholesterol in the microemulsion system lowered the intensity ratio, indicating that the hydrocarbon chain experienced more bending and kinking in the presence of cholesterol. The effect of various anaesthetics on the chain conformation of a hydrocarbon monolayer was also studied by laser Raman spectroscopy.