A new cycloartane sapogenol and a new cycloartane xyloside were isolated from Astragalus karjaginii BORISS along with thirteen known compounds. The structures of the new compounds were established as 3-oxo-6 alpha,16 beta,24(S),25-tetrahydroxycycloartane (1) and 6-O-beta-D-xylopyranosyl-3 beta,6 alpha,16 beta,24(S),25-pentahydroxycycloartane (2) by 1D- and 2D-NMR experiments as well as ESIMS and HRMS analyses. The presence of the keto function at position 3 was reported for the first time for cyclocanthogenol sapogenin of Astragalus genus. In vitro immtmomodulatory effects of the new compounds (1 and 2) along with the n-BuOH and MeOH extracts of A. karjaginii at two different doses (3 and 6 mu g) were tested on human whole blood for in vitro cytokine release (IL-2, IL-17A and IFN-gamma) and hemolytic activities. The results confirmed that compound 2, a monodesmosidic saponin, had the strongest effect on the induction of both IL-2 (6 mu g, 6345.41 +/- 0.12 pg/mL ( x 5), P < 0.001) and a slight effect upon IL-17A (3 mu g, 5217.85 +/- 0.72 pg/mL, P < 0.05) cytokines compared to the other test compounds and positive controls (AST VII: Astragaloside VII; and QS-21: Quillaja saponin 21). All tested extracts and molecules also induced release of IFN-gamma remarkably ranging between 5031.95 +/- 0.05 pg/mL, P < 0.001 for MeOH extract (6 pg) and 5877.08 +/- 0.06 pg/mL, P < 0.001 for compound 1 (6 pg) compared to QS-21 (6 mu g, 5924.87 +/- 0.1 pg/mL, P < 0.001). Administration of AST VII and other test compounds did not cause any hemolytic activity, whereas QS-21 resulted a noteworthy hemolysis.