The antiproliferative activity of three benzopyrans isolated from the chloroform extract of the aerial parts ofHypericum polyanthemumwas analysed in order to determine their effect on the growth and cell cycle in the U-373 MG glioblastoma cell line. Compound 1 was less cytotoxic than compounds 2 and 3. A synergistic effect was noticed when the three benzopyrans were used simultaneously. The cytotoxicity noted could be related to an arrest in G2/M phase, leading to apoptosis in the U-373 MG glioblastoma cell line. Copyright © 2008 John Wiley & Sons, Ltd.