Ibuprofen is a propionic acid derivative, non-steroidal drug provided with a very effective anti-inflammatory and analgesic actions and an increased antipyretic effect The main purpose of this research was to establish and develop an effective spectrophotometric method to exactly quantify and verify the Ibuprofen amount from three different pharmaceuticals, according to the Rules of Good Pharmaceutical Practice provided by the International and European Pharmacopoeias. By spectrophotometric proposed method. Ibuprofen quantitatively reacted with alcoholic alpha-naphthylamine 0.1 % and sodium nitrite NaNO₂ 5%-6%, by heating at 72-73ºC for 20 minutes. It was observed the quantitative synthesis of orange azo dye with a pale yellowish tint, dosed in the Visible (VIS) field at λ = 466 nm, in relation to absolute ethanol as a blank. For the first pharmaceutical product, pure Ibuprofen amount determined at λ = 466 nm was found to be 598.750 mg. This amount found was assigned to a mean percentage content of 99.792 % , provided with average percentage deviation of only 1,958 %, below the officially maximum stated value ± 5% and was very close to the officially declared content (600 mg). Regarding the second and third pharmaceuticals, calculated amounts of Ibuprofen were 394,774 mg corresponding to 98,694% Ibuprofen and 197,780 mg assigned to 98,890 % pure Ibuprofen content , respectively. These determined amounts for the second and third products were very close to the officially stated amounts of 400 mg and 200 mg ,and presented average percentage deviations (+) 1,306 % and (+) 1.110 %, both located below the maximum allowed percentage value ± 5% , officially stated by European and International Pharmacopoeias Rules.