The study performed in the years 2002-2004 determined seed germination and the occurrence of fungi on and in the developing seeds of oilseed rape. What was also examined was the correlation between the occurrence of Alternaria and Cladosporium spp. spores in the air and seed infestation with the fungi. The highest values of seed germination were observed in 2003. The composition of fungi varied depending on the year and the stage of seed development. Irrespective of the year and the position on a plant, Alternaria and Cladosporium spp. were the dominating fungi detected on the oilseed rape seeds. The majority of fungi contaminated the seed surface. Cladosporium spp. occurred at high percentages from the early stages of seed development, whereas the highest percentages of Alternaria spp. were detected at the end of seed maturation. The number of fungi infecting the seed coats and the embryos increased during the seed development. Towards the end of maturation, more fungi were detected in the seed coat and the embryo of the seeds from the secondary branches as compared with those obtained from the main racemes. The spores of Cladosporium and Alternaria spp. were present in the air throughout the whole observation period. The number of the Alternaria spp. spores in the air increased with time, reaching the highest values at harvest. Cladosporium spp. spores occurred in the air at high concentrations from the very beginning of the observation period. The highest concentration of Cladosporium spp. spores in the air was recorded in 2004. The correlation coefficients between the number of Alternaria and Cladosporium spp. airborne spores and the percentages of the seeds infested with the fungi were not statistically significant.