Measurements have been made to determine gamma ray attenuation coefficients very accurately by using a narrow-collimated-beam method which effectively excluded corrections due to smallangle and multiple scattering of photons. Mass (μ/ρ) and linear attenuation coefficients (μ) of Al for 514, 662 and 1280 keV gamma-rays photons have been measured using the well-type scintillation spectrometer. The values of μ and μ/ρ thus obtained are found to be in good agreement with the theory.