To maintain and rehabilitate the ecosystem, the protection of water from anthropogenically derived pollutants is one of the important tasks in environmental science. From this perspective, the quality of rainwater and roof runoff were investigated in this case study, which showed that the av. sum concns. of polycyclic arom. hydrocarbons (PAHs) and n-alkanes are greater in rain than in roof runoff. The concn. of most PAHs in rainwater is irregular and remains in roof runoff almost const. during the rainfall process. The sum concns. of PAHs and n-alkane are higher in winter and autumn than in summer and spring. N-alkanes seem to be derived mainly from anthropogenic sources.