This Investigation was carried out at Nubaria Agricultural Research Station (30° 54´ N, 29° 57´ E, and 15m above sea level), Agricultural Research Centre (ARC), Ministry of Agriculture and Land Reclamation (MALR), El-Behiera Governorate,  Egypt, during 2016-2018 period to study the effects of application liquid humic acid on alfalfa forage yield and quality under irrigation water regime.  Three irrigation water regime treatments were100%, 80% and 60% of ETp and three humic acid rates  0, 3 and 6 L/ha humic acid  were tested  in a strip-plot design. As water requirements decreased forage yield significantly decreased, in the 4 seasons for each year. No significant differences were found between the fresh or dry forage yields or leaf/stem ratio under 100% water requirement without humic acid and 80% water requirement with 6 L/ha humic acid. No significant differences were found between protein content under the interaction between irrigation water requirements and humic acid rate. Irrigation water use efficiency increased under water stress as an application of humic acid rate increased. The previous results indicate that, under experimental conditions, it is possible to save 20% of the amount of added water when adding   6 L/ha humic acid    with an insignificant increases in yield amount to 11.421 t /ha.