Galium verum, also known as Lady's Bedstraw, is a herbaceous perennial plant of the family Rubiaceae, native to Europe and Asia and used in traditional medicine as an anticancer medicine. It is used as a decoction in most traditional recipes, applied externally as well as internally. We produced a Galium verum decoction and applied it in vitro to chemosensitive (Hep-2 and HLaC79) and chemoresistant, P-glycoprotein-overexpressing (Hep2-Tax, HLaC79-Tax) laryngeal carcinoma cell lines. It could be demonstrated that Galium aqueous extract is cytotoxic for all cell lines. A detailed spheroid-based 3D invasion analysis of Hep2 and Hep2-Tax in semisolid collagen gels and on different extracellular matrix coatings was performed, which showed an inhibition of invasion by sublethal concentrations of Galium decoction and proved to be even more pronounced in the more aggressively invading chemoresistant Hep2-Tax cell line. Gelatinolytic activity of MMP-2 was downregulated in three of the four cell lines. Angiogenesis (endothelial tube formation) in contrast, was not affected by Galium aqueous extract. Gene expression array on HLaC79 and Hep2 cell lines treated with Galium decoction vs. untreated controls revealed no unique pathway activation patterns in these cells. Results are discussed with respect to the use of herbal drugs as a preventive and/or a concomitant therapeutic approach in head and neck cancer.