The present study was conducted to investigate the effects of different irrigation levels (100, 75, 50 and 25% of field capacity) on above and underground organic biomass production of commonly grown Hungarian vetch (Vicia pannonica Crantz) and field pea (Pisum arvense L.). Experiments were carried out in laboratories in Field Crops Department of Canakkale Onsekiz Mart University between the dates 15.11.2014 and 15.05.2015. Experiments were conducted in randomized plots design with 4 replications. Current findings revealed that irrigation water levels significantly affected plant height, aboveground fresh and dry biomass, aboveground dry matter ratio and underground biomass of Hungarian vetch an Field Pea. The greatest plant height, aboveground fresh and dry biomass, dry matter ratio and underground biomass of both forage plants were obtained from 75% irrigation level. The plants produced the least organic matter at the lowest irrigation level. It was concluded that irrigations in Hungarian vetch and field pea should be initiated when the available soil moisture level dropped to 75% of field capacity.