Leaf surface fungi are considered major contributors to the air spora. Although airborne spores occur year round in the Tulsa atmosphere, levels begin increasing in April and typically reach peak levels in the fall. April is also the time when deciduous trees in the area begin putting out leaves. The current study was undertaken to determine the early colonizers of leaf surfaces and compare these taxa to those occurring in the atmosphere. Leaf and air samples were collected in April. Air sampling was carried out with a Burkard Spore Trap located on the roof of a building on campus. The sampler was set for 7-day sampling onto Melenex tape that was coated with a thin film of Lubriseal. Each week the drum was changed and the tape cut into one-day segments. These were stained with glycerin-jelly mounting medium and examined microscopically at 1000X. Leaf samples were aseptically collected from Ulmus and Quercus trees on campus during April, placed in sterile plastic bags, and brought to the lab. For each leaf, 4 cm² areas of both upper and lower leaf surfaces were separately wiped with a sterile cotton swab. Each swab was then washed in 1 ml of sterile distilled water. The resulting spore suspension was dilution plated on malt extract agar with streptomycin. Cultures were incubated at room temperature for 5 to 7 days and then examined microscopically. Results are expressed as colony forming units (CFU)/cm². Air samples from April 2002 and previous years show that Cladosporium conidia were the dominant spore type in the atmosphere followed by ascospores. During April, Ulmus leaves averaged 15.5 CFU/cm² and Quercus leaves averaged 28.6 CFU/cm². On Ulmus, Cladosporium followed by yeast and Alternaria were the leading fungi isolated, while the dominant fungi on Quercus leaves were yeast followed by Cladosporium and Phoma type colonies. However, it should be noted that as many as 14 different types of fungi were isolated from the leaf surfaces within one week of bud break. Although leaf surface fungi are known to contribute to the air spora, our data also suggest that airborne fungal spores may be the initial source of inoculum for leaf surface colonization. Further work is needed to determine if these leaf surface fungal communities are consistent throughout the growing season, or show a succession that parallels changes in the air spora.