Simple colourimetric method for the estimation of mosapride citrate in solid dosage forms is described. Estimation of mosapride citrate is based on diazotization of mosapride and coupling of the diazonium salt with N-(1-napthyl) ethylene diamine dihydrochloride to form a stable purple colored chromogen. With absorbance maxima at 540 nm the chromogen obeyed linearity over 20 to 160 $\mu$g/ml.