The distribution and source of 16 polycyclic aromatic hydrocarbons (PAHs) in Henan Reach of the Yellow River, Middle China, has been investigated. summation sigmaPAHs levels ranged from 144.3 to 2361 ng L(-1) in water, from 506.6 to 10,510 ng g(-1) in suspended particulate matters (SPMs) and from 16.4 to 1358 ng g(-1) in sediment, respectively. The compositional profile of PAHs revealed that 2-3-ring PAHs were predominated in water and 2-4-ring PAHs were abundant in SPMs. Whereas the PAHs in sediment were composed mainly of 3-5-ring PAHs. The spatial distribution of PAHs indicated that concentrations of PAHs in water and SPMs in dry season were much higher than those in flooding season. It may be attributed to a high flow rate in flooding season. The ratios of phenanthrene/anthracene (Phe/Ant) and fluoranthene/pyrene (Flua/Pyr) reflected a pattern of pyrogenic input. The potential ecosystem risk assessment indicated that the ecosystem risk of PAHs was relatively low in Henan Reach of the Yellow River.