Myxomycetes (slime molds) are ideal model organisms for population dynamics studies in terrestrial forest habitats. This research assessed the occurrence and distribution of myxomycetes in selected highland areas of three provinces in Luzon Island, Philippines. Myxomycetes present in the moist chambers of aerial and ground leaf litter, twigs, and dead barks of living trees were recorded and used to assess their abundance and diversity for each of the study sites. The obtained results showed that 51% of prepared moist chambers yielded myxomycetes. Identification of the collected myxomycetes resulted in 25 species belonging to 7 genera including Arcyria, Comatricha, Diderma, Didymium, Perichaena, Physarum, and Stemonitis. Physarum decipiens is reported as a new record for the Philippines. Four species including Arcyria cinerea, Comatricha nigra, Physarum album, and Stemonitis fusca were the most abundant. Many species were reported as rare. Our research showed similarities in the distribution of myxomycete assemblages in the study areas with closer proximities.