Somatic chromosomes at mitotic metaphase of two species and two undescribed populations of Bowenia, and Stangeria eriopus, which were classified in Stangeriaceae, Cycadales, were compared using the standard aceto-orcein staining method. All Bowenia taxa showed a chromosome number of 2n = 18, while S. eriopus showed a chromosome number of 2n = 16. The chromosome number of 2n = 18 in B. ‘Kuranda’ is reported for the first time. The present karyotype analysis indicates that B. ‘Kuranda’ and another undescribed taxon, B. ‘Tinaroo’, are cytotaxonomically closer to B. spectabilis than B. serrulata, and that the karyotype of Stangeria is unlikely to have been derived from that of Bowenia by a simple chromosomal change such as centromeric fission and deletion.