During our studies of plants with cytotoxic (KB) activity or life-prolongation activity in mouse leukemia assays (P-388 or L-1210), it was found that a crude EtOH extract of Anopterus glandulosus Labill. (Escalloniaceae) exhibited high activity in the P-388 (T/C 193 at 50 mg/kg) and KB (ED₅₀ 5×10⁻¹ µg/ml) systems, and, consequently, fractionation studies were initiated. There are only two known Anopterus species, both restricted in distribution to Australia, Anopterus maleuyanus F. Muell. is a tree found in southern Queensland, and A. glandulosus is a small Tasmanian tree. The alkaloids of A. maleuyanus were first examined by Hart et al. (1,2) who discovered several novel bases with an ent-kaurenoid skeleton. Although the alkaloids were reported to have activity in the KB and P-388 assays, no details were presented (1), and no bases were isolated in crystalline form from A. glandulosus, which has a much lower alkaloid content. More recently we have presented a preliminary report of the alkaloids of A. glandulosus (3). Subsequently a 2D-nmr study by Johns et al. (4) has clarified the uncertain position of one hydroxyl group present in some of the bases. In this report we present a full account of the isolation and structure-activity relationships found in the ent-kaurene alkaloids isolated from A. glandulosus, including the isolation of two new bases. Details of structural elucidation will be limited because all of the compounds 1-5 have now been described (1,2,4). The observed biological activity was not due to the non-alkaloidal components as this fraction was inactive in the KB and P-388 test systems.