This research was conducted during the period from August 2007 to October 2007 in the Fundo Miraflores of the National University of San Martin, Ahuashiyacu, District Band Shilcayo, Province of San Martin, Department of San sectors Martin; in order to determine the effect of different doses of biol applied in folear form on the cultivation of cowpea variety "san roque ~ and benefit / cost ratio. The factors studied were composed of the cowpea crop variety "San Roque" with different doses of Biol (T1 = 40Lt / ha; T2 = 60lt / ha; T3 = 80lt / ha); T4 = Control Chemical and T5 as absolute Witness .The experimental design was complete block design at random (DBCA), which consisted of 5 treatments and 4 repetitions. The results indicate that the best dose of biol both greater plant height, number of pods per plant, number of seeds per plant, and a higher yield per hectare I got the (T2 = 60lt ...