The physiological seed quality of annual ryegrass produced in the State of Rio Grande do Sul, Brasil, was studied in the season of 1995. For its evaluation, the following tests were applied: physical purity (purity analysis, moisture content and weight of 1000 seeds); viability (germination test) and vigor (first count of the germination test, germination speed index and accelerated aging), leading to the conclusions that 47%, of the studied samples, showed purity and germination according to the official standard grades in the State of Rio Grande do Sul; for germination, 81% attended the standard germination index required for commerce and 54% showed the standard for physic purity; no prohibited weeds were found; for the vigor, the first count test would approve only 56% and the accelerated aging only 53% of the studied samples, when it was taken as reference the minimum germination (70%) of the official standars commercialization of the ryegrass seeds in the State of Rio Grande do Sul.