In this work, total phenolic and flavonoid contents and antioxidant activities in methanol and aqueous extracts of five-high altitude medicinal plants namelyAconogonon tortuosum, Thlaspi arvense, Erysimum bhutanicum, Thalictrum chelidoniiandAletris pauciflorawere studied for the first time from Bhutan. Antioxidant activities were investigated using DPPH radical scavenging activity (DRSA), ferric reducing antioxidant power (FRAP), superoxide dismutase (SOD) and catalase (CAT) assays. Significant level of phenolics and flavonoids were found in all medicinal herbs. Among the five plants studied, aqueous extract ofThalictrum chelidoniiand methanol extract ofErysimum bhutanicumshowed best free radical scavenging activity. Both aqueous and methanol extracts ofAconogonon tortuosumshowed strong ferric reducing antioxidant power. The results indicate that all five medicinal herbs could be potential sources of natural antioxidant compounds and could help boost the immune system of patients.