The preparation of novel biologically active platinum(II) and palladium(II) complexes of some β-carboline alkaloids (harmaline, harmalol, harmine, and harmane) is described. These complexes, characterized on the basis of their CHN elemental analysis, infrared, Raman, and 1H and 13C nuclear magnetic resonance spectral data, were shown to have the empirical formula [M(alkaloid)Cl 2], M = Pt, Pd. The antitumor and antiviral activities of some of these complexes have been demonstrated.