Abstract: In the present study, a new economic, rapid and inexpensive bacterial micro-assay for simultaneous detection and quantitative measurement of serum galactose was developed. Quantitative measurement of galactose in the serum of galactosemia patients is necessary to confirm the disease.Analysis of the standard curve showed a broad linearity range for galactose from 2 to 180 mg dL–1 with a regression equation of Y = 0.013-0.083; R2 = 0.962. The advantage of the method is its ability to measure serum galactose quantitatively. The cost per sample is about 20-50 cents, which is much less than HPLC and enzymatic commercial kits. The method can be automated which is suitable for galactosemia neonatal and mass screening especially in developing countries in which funding is a limiting factor.