A low cost, selective and sensitive method was developed for diagnosis of some diseases such as Histidinemia, Alzheimer, Rheumatoid arthritis and inflammation in obese women. The assessment of the histidine based upon the quenching of the luminescence intensity of the nano Eu–Norfloxacine complex doped in sol–gel matrix optical sensor. The measurements were carried out at (the main emission band of the optical sensor) 617nm in acetonitrile at pH 7.6, λex=380nm, in the presence of different concentrations of histidine. The influence of the different parameters, e.g. pH, solvent, histidine concentration and foreign ions that control the luminescence intensity of the nano optical sensor Eu–Norfloxacine complex doped in sol–gel matrix were studied. The remarkable quenching of the luminescence intensity of nano optical sensor Eu–Norfloxacine complex in acetonitrile at 617nm by various concentrations of histidine were successfully used as an optical sensor for the assessment of histidine concentration. The calibration plot was achieved over the concentration range 5.0×10−6–1.0×10−9mol/L histidine with a correlation coefficient of 0.993 and a detection limit of 6.5×10−10mol/L.