Two fossil poroid hymenophore fragments, one Cretaceous, the other Eocene, were obtained from marine calcareous concretions collected on Vancouver Island, British Columbia. Cellulose acetate peels of these permineralized tissues allowed us to determine the size and distribution of pores in the hymenophores and to examine the hyphal anatomy of the dissepiments and some hymenial elements. In the Cretaceous specimen, pores are round to elliptical, 3 per mm, and 130-540 mm diam. Dissepiments consist of narrow, simple septate, hyphae. Neither basidia nor basidiospores are present, but acuminate, thin-walled hymenial cystidia, up to 54 mm in length, are common. The Eocene specimen has a pore density of 6 per mm and pores are 130-163 mm diam. Dissepiments consist of narrow, simple septate, thin-walled hyphae. Neither basidia nor basidiospores are present, but acuminate, thick-walled hymenial cystidia, up to 32 mm in length, are common. The poroid hymenophore is a characteristic of a number of extant basidiomycete taxa, including the Boletales, Poriales and Hymenochaetales. It is unlikely that the fleshy, ephemeral, terrestrial basidiomata of the Boletales would be preserved in a marine environment and thus the specimens are interpreted as belonging to basidiomycete lineages with persistent, leathery or corky basidiomata. These fossil specimens unequivocally push back the minimum age of homobasidiomycetes and extend the paleogeographical range of this fungal phylum.

Key words: Aphyllophorales, Cretaceous, Eocene, fossil fungi