Price trend data since 1978 indicate a seasonal increase in lamb (Ovis aries) prices during spring and early summer. This seasonal price increase occurs over the same period as lamb weight gains observed from previous grazing trials with wheatgrass (Agropyron and Thinopyron spp.) and wheatgrass-sainfoin (Onobrychis spp.) mixtures. Little information is available on the economics of lamb production from these forages on the Southern Great Plains. Our objective was to determine the potential profitability of spring lamb production from three irrigated wheatgrasses, ‘Hycrest’ [A. cristatum (L.) Gaertner × A. desertorum (Fischer ex Link) Snuiters], ‘Luna’ [T. intermedium subsp. barbulatum (Schur) Barkw. and D.R. Dewey], and ‘Jose’ [T. ponticum (Podp.) Barkw. and D.R. Dewey] grown alone and with ‘Renumex’ sainfoin (O. viciifolia Scop.). Replicated pastures grown on a Pullman clay loam (fine, mixed, thermic Torrertic Paleustoll) were rotationally grazed (dry matter allotment of 6.5% of body wt/d) by weaned Rambouillet × Suffolk wether lambs for an average of 77 d in spring of 1987 and 1988. Lamb production ranged between 142 and 420 lb/acre. Gross margins per acre for lamb production were Hycrest, −$85; Luna, −$5; Jose, −$48; Hycrest-sainfoin, $83; Luna-sainfoin, $91; and Jose-sainfoin, $64. Our results showed that despite fluctuations in lamb output price, lamb production from wheatgrasses grown with sainfoin was more profitable than from wheatgrasses grown alone.