Some herbaceous legumes have shown a dry tolerance and had been used as animal feed. However, some of those plants have anti nutritional compounds such as tannins that can interfere on intake and digestibility. Tannins are polyphenolic compounds originated in a secondary metabolism of the plant as protection against insects, birds and as a result of drought, temperature or soil fertility. In order to preserve the tannin for experimental purposes, it is suggested that the hay preparation should be made under shadow. The objective of this work was to compare the concentration of phenolics compounds in forage legumes havested in dry and wet seasons and under sun, shadow and air circulation dry.