Samples of Nereocystis luetkeana, an edible brown algae, were collected from Puget Sound, Wash. The freeze-dried samples were analyzed for proximate and elemental composition and evaluated for protein quality by amino acid analysis and using Tetrahymena pyriformis W. The freeze-dried frond, stipe, and bulb of the algae showed similar composition; however, the frond had a protein content twice that found in the bulb and stipe and five times less crude fiber than the stipe. The proximate analysis of the frond was 15.3% protein, 1.3% crude fiber, 42.7% ash, 1.9% crude fat, and 38.8% carbohydrate (by difference). Based on neutron activation analysis, Nereocysti: contained appreciable quantities of sodium, potassium, calcium, and iron. The algae protein appeared to be of high quality based on growth of Tetrahymena pyriformis W. on a pepsin digest of the algae and on the amino acid profile and in vitro digestibility of the intact algae.