An absorption spectrometer consisting of a near-infrared laser diode was constructed and used for the determination of phosphorus in milk. This determination was also carried out with a UV-VIS spectrophotometer. The spectrometric instruments were compared for the determination of the phosphorus content of sterilized milk; sheep and goat milk, Jersey, Brown Swiss and Simmental cows' milk, skimmilk powder and whey powder. The optimum experimental conditions were investigated, and the analytical characteristics of the two instruments, using standard International Dairy Federation (IDF) method, were evaluated. They were compared in terms of their linearity, reproducibility and precision. The coefficients of variation were 3.4% for NIR-LD and 4.5% for UV-VIS spectrometers. Data obtained by using both instruments showed that NIR-LD spectrometer could be used as an alternative to UV-VIS spectrometer for the determination of phosphorus content in milk and milk products with better precision.