Previous studies have suggested that phytomedicinal preparations from bloodroot (Sanguinaria canadensis L.) may harbor immunomodulatory properties. The purpose of this investigation was to determine the effects of alcohol tinctures and water infusions generated from bloodroot flowers, leaves, rhizomes, and roots on human peripheral blood mononuclear cell (PBMC) cytokine production and proliferation in vitro. PBMCs were collected from 16 healthy young adults and cultured with bloodroot extracts or respective controls for interleukins-1β, -2, -8, -10, interferon-γ, and tumor necrosis factor. Proliferative capabilities of both PBMCs and K562 cells (an immortalized human myelogenous leukemia cell line) following extract treatment were determined. High-pressure liquid chromatography was used to quantify berberine, chelerythrine, and sanguinarine in the extracts and to correlate extract composition with observed effects. Overall, infusions demonstrated greater immunomodulatory capabilities than tinctures, and flower-and root-based extracts showed greater immunomodulatory properties than leaf-or rhizome-based extracts (some effects seen with rootbased extracts may be due to endotoxin). Several extracts were able to augment PBMC proliferation and diminish K562 proliferation, suggesting a selective anti-carcinogenic activity. The rhizome alcohol tincture had a markedly stronger effect against K562 cells than other extracts. Chelerythrine, sanguinarine, and endotoxin (but not berberine) sometimes correlated with observed effects. The in vitro activities demonstrated here suggest bloodroot extracts may have potential as therapeutic immunomodulators.