Although the genetic aspects of mating are a rapidly expanding field of study, little information is available for the genus Ophiostoma. The first MAT information for the genus focussed on only three species and this was as such, hardly representative of the genus. In this study, existing DNA sequence data were used as a starting point to expand the available knowledge on mating genes to other species of Ophiostoma. Ophiostoma quercus, one of the better-studied species of Ophiostoma was the focus of the initial investigation. The heterothallic mating strategy of O. quercus was confirmed and isolates of both mating-types were used for the molecular analysis of the MAT genes. Regions of both MAT idiomorphs were observed in both mating-type isolates. This discovery was unexpected and suggests an unconventional mating organisation for O. quercus as compared to other heterothallic fungal species. Such a system is not unprecedented for fungi, but is unique for the genus Ophiostoma. The primers developed for O. quercus were tested in isolates representing 17 species of Ophiostoma. These primers were used successfully to amplify a large segment of the MAT-2 idiomorph in all isolates tested. This significantly expanded on the amount of data available for the MAT genes of Ophiostoma. Analysis showed that these isolates share a high amount of conservation in the MAT-2 open reading frame. This region of the genome is, therefore, not useful for phylogenetic analyses. However, the availability of primers for the region might facilitate testing of other areas of the full idiomorph for phylogenetic inference. Overall, the results presented in this study represent a significant increase in the knowledge available on MAT genes in Ophiostoma. Copyright / Dissertation (MSc)--University of Pretoria, 2009. / Genetics / Unrestricted