Context. The diversity of myxomycetes associated with Australia’s most diverse native conifer genus, Callitris, has been incompletely studied. Aims. In this study, we examine the diversity of myxomycetes associated with outer bark, fallen cones and dead litter (leaves/ needles) of four Callitris species. Methods. Substrate samples were collected from 13 localities in New South Wales, Queensland and the Northern Territory. Samples were used to prepare moist-chamber cultures, and species of associated myxomycetes were identified. Key results. Twenty-three species in 15 genera were recorded. Percentage occurrence of myxomycetes varied depending on substrate, being 87% (cones), 83% (bark) and 63% (litter). Bark yielded the most species (17), followed by litter (10) and cones (6). Only two species ( Arcyria cinerea and S. fusca) were recorded from all three substrates. Substrate pH is often an important factor for the occurrence of myxomycetes, but the mean values recorded for cones (5.7), litter (5.8), and bark (5.9) showed little difference. This suggests that other undetermined factors contributed to the differences in species occurrence. In addition to the records generated in the present study, we provide a list of previous records of myxomycetes found in association with Callitris. Conclusions.This study has highlighted, for the first time, the diversity of myxomycetes associated with members of the genus Callitris and has shown the importance of cypress pines as a substrate for myxomycetes. Implications. This study leads to a better understanding of the biogeography, distribution and ecology of myxomycetes and their associated organisms.