Abstract: Ergine and ergonovine contents in leaf blades, pseudostems, leaf sheaths, roots and seeds of four populations of Elymus dahuricus infected by grass endophyte (Neotyphodium) from Wulingshan (WLS), Qinyuan (QY), Wutaishan (WTS) and Baiwangshan (BWS), were detected in April, June, August and October of 2009 using high performance liquid chromatography. In April, June, and August the highest contents of ergine were detected in leaf blades (5.037-30.037 mg/kg) and sheaths (6.259-22.255 mg/kg), while in October the highest values were found in the seeds (5.045-8.971 mg/kg) and leaf blades (3.119-6.658 mg/kg). Ergine contents in leaf blades, pseudostems and leaf sheaths in April or June (13.831-30.037 mg/kg) were significantly higher than those in August or October (3.119-6.658 mg/kg). Ergine contents in the roots in August (0.552-0.576 mg/kg) were significantly lower than those in other months. The distributions of ergonovine in different tissues showed a similar pattern to those of ergine. The highest contents of ergonovine were detected in leaf blades (2.206-8.226 mg/kg) and sheaths (0.268-5.490 mg/kg ) in April, June and August, while in October the highest values were also found in the seeds (1.647-5.664 mg/kg) and leaf blades (1.353-2.251 mg/kg). Ergonovine contents in leaf blades, pseudostems and leaf sheaths in April or June (5.102-8.226 mg/kg) were significantly higher than those in August or October (1.353-2.251 mg/kg). The lowest contents of ergonovine were found in August (0.128-0.283 mg/kg). The contents of ergine and ergonovine in the whole plant of these four populations were different in different months. Ergine contents were significantly higher than ergonovine contents in total ergot alkaloids. Ergine contents were significantly linearly correlated with ergonovine contents.