Forage trials of seeded perennial grasses were conducted at four sites in three areas of southcentral Alaska on soils with pH readings generally below 5.5 (down to 4 .35) . Three trials were at forested locations and one at a subalpine site. Each trial was sustained for three to five harvest years under a two-harvest system. 'Engmo' timothy (Phleum pratense) , the standard forage grass on strongly acidic soils in the region, equaled or, more often , exceeded the other grasses in first-harvest yields, but often was surpassed in second-harvest yields. Grasses often substantially exceeding timothy in second-harvest yields included reed canarygrass (Phalaris arundinacea) and entries of tufted hairgrass (Deschampsia caespitosa) and Bering hairgrass (D. beringensis), sometimes providing more total yield than timothy. Some red fescues (Festuca rubra) and 'Nugget' Kentucky bluegrass .(Poa pratensis) also tended to surpass timothy in second growth. Smooth bromegrass (Bromus inermis) failed at sites with soil pH below 5.3, but persisted at one site with pH varying from 5.3 to 5.7. 'Garrison' creeping foxtail (Alopecurus arundinaceus) also failed at these sites; its close relative meadow foxtail (A. pratensis), was better adapted to the strongly acidic sites. Indigenous polargrass (Arctagrostis latifolia) about equaled or surpassed timothy in yield at two of the sites, and bluejoint reedgrass (Calamagrostis canadensis) provided comparable but somewhat lower yields. Timothy tended to be higher in digestible dry matter than most grasses, but near to below average in CP, P, K, and Ca concentrations. Some deficiencies occurred in energy values (DDM) and, except for red fescue, in Ca concentrations of first-harvest herbage relative to the requirements of a growing 500-lb steer. Crude protein of second-harvest herbage was deficient for many grasses at two sites, and DDM was marginal to low for some, but especially for bluejoint reedgrass.