Cassava (Manihot esculenta Crantz) is a major root crop in the tropics and its starchy roots are significant sources of calories for more than 500 million people worldwide. Cassava breeders aim to produce many clones rapidly with desired agronomic traits. Near-infrared spectroscopy (NIRS) is a physical detection method that was developed in recent decades. This technique is based on the correlation between chemical properties and the absorption of light at specific wavelengths in the near-infrared region. A rapid and accurate method for determining dry matter (DM) content of cassava root will be valuable and help the breeders in selecting clones with good traits. The objectives of this SOP were to calibrate Near-infrared spectroscopy (NIRS) using a portable ASD spectrophotometer for analysis of fresh intact and mashed cassava roots, and to make a comparison between both methods so as to identify which gives the best prediction equation. Fresh intact and mashed cassava roots were analyzed for dry matter content. The near-infrared (400-2400 nm) spectra of the samples were measured. Calibration equation with cross validation were computed using partial least squares method. The quality of prediction was evaluated by root mean square (RMS) and r2 parameters between the predicted values from cross-validation. The dry matter content was predicted with 95% confidence (r2 = 0.995) for the mashed roots which gave mean RMS value of 19193 and 12135 for the two genotypes, and 77% (r2 = 0.771) for the intact roots which gave a mean RMS values of 47686 and 42255 respectively.