The concentration of 16 polycyclic aromatic hydrocarbons (PAHs) in the gasoline combustion products emitted into the atmosphere by internal combustion engines (ICE) has been measured using the gas chromatography method. The concentrations of PAHs in the exhaust gases sampled behind a catalytic converter has been determined when the ICE operates in five modes: idle mode, high speed mode, load mode, ICE cold start mode (engine warm-up) and transient mode. Using 92 RON, 95 RON and 98 RON gasoline the effect of the octane number of gasoline on the PAHs content in the exhaust gases has been revealed. The concentration of the most carcinogenic component (benzo(α)pyrene) in the exhaust gases behind a catalytic converter significantly exceeds a reference value of benzo(α)pyrene in the atmospheric air established by the WHO and the EU for ICE in the load mode.