When the pyrrolizidine alkaloids heliotrine and lasiocarpine were incubated in vitro with sheep’s rumen contents, a common metabolic product was formed. Thiscompound was also found as an end-product of metabolism in the rumen contents of sheep fed on a ration containing the plant Heliotropium europaeum. Previously described rumen metabolites of the Heliotropium alkaloids were 1-methylenepyrrolizidine derivatives, e.g. I-goreensine. The newly found product represents a further stage of reduction of 1-goreensine in which the 1-methylene group has been replaced by a 1-methyl group. This compound has been identified as 7α-hydroxy-1α- methyl-8α-pyrrolizidine, a previously unknown pyrrolizidine derivative. © 1970, CSIRO Publishing.