Simple, rapid and accurate, spectrophotometric method for the determination of losartan potassium by using bromothymol blue as a chromogen and phosphate buffer solution (pH 3-4) as a diluting agent was developed. The developed colour shows maximum absorbance at 620 nm and it was observed that the absorbance of different dilution from the plots the calibration curve between the concentrations in x-axis, absorbance at y-axis. The recovery studies were also carried out to ensure the reproducibility and repeatability. This recovery studies shows between 96.82-100.08% for the different formulation. Hence, it was concluded that the developed simple, precise and accurate method can be effectively used for the routine analysis of losartan potassium