AbstractFree and conjugated sapogenins (saponins) were analysed by GC-MS in N. ossifragum plant parts (leaves, stems, flower heads and roots) collected from sites in Auchtertyre Farm, Strathfillian, West Perthshire, Scotland on which sheep were photosensitized. Smilagenin and sarsasapogenin acetates were detected in acetylated extracts. The amount of conjugated (glycosylated) sapogenins in leaf samples, except the basal region of mature plants from site 3, was 2040-4618 mg/kg dry matter. The presence of substantial levels of conjugated sapogenins in the flower heads of young plants from site 1 (approximately 18 g/kg dry matter), and of free sapogenins in the roots of plants from sites 1 and 3 (832 and 1184 mg/kg dry matter, respectively) was detected.