The use of phenol and alkaline hypochlorite has been investigated for the spectrophotometric estimation of methylamine. The reagents react with methylamine forming an intensely blue colored dye, the maximum absorption for which is observed at 630 nm. The rate of the reaction is slow. Sodium nitroprusside is added to enhance the sensitivity and rate of the reaction. The rate is also enhanced by raising the temperature of the reaction. The formation of the indophenol dye is pH sensitive, maximum intensity being observed at pH 10.5. The reaction mixture buffered at pH 10.5, is thermostated at 37°C and its absorbance measured at 630 nm after 3 hours. The system obeys Beer's law up to 15 ppm with slight deviation in the lower ranges. Concentrations as low as 0.5 ppm of methylamine can be estimated in a 1 cm cell.