Five loline-type alkaloids, the known lolinine, N-formylloline, loline, N-methylloline and the new 5,6-dehydro-N-acetylloline, were characterized from the pooid-grass endophyte-infected Festuca argentina. These compounds are not responsible for the toxicity of the plant, as shown upon i.p. injection into mice. Their probable phytoalexine role and chemotaxonomical significance are discussed.