Three new quinoline alkaloids, thalicalkaloids A-C (1-3) together with three known alkaloids were isolated from the whole plant of Thalictrum atriplex. Their structures were elucidated by spectroscopic methods, including extensive 1H, 13C, and 2D-NMR techniques. Compounds 1-6 were tested for their antibacterial and anti-rotavirus activities. The results revealed that compound 3 exhibited high anti-rotavirus activity with therapeutic index (TI) valves of 24.0, and this valve is close to the positive control. Compounds 1, 2, 4-6 also showed potent anti-rotavirus activities with therapeutic index (TI) valves in the range of 11.0~15.8, respectively. In addition, compounds 1-6 showed good antimethicillin- resistant Staphylococcus aureus (anti-MRSA) activities with IZD of 12.2±1.5, 15.8±1.4, 14.5±1.2, 12.6±1.2, 13.4±1.4, and 14.0±1.5 mm, respectively. © 2022 The Japan Institute of Heterocyclic Chemistry.