Testing for the presence of various PAHs was done on water samples taken from the River Niger at Onitsha. Using the GC-FID method, water samples collected from five sampling sites designated (001 - 005) were assessed. The amounts of 14 PAHs in water samples have been measured. The range of the mean concentration (g/l) of each PAH in water was as follows: 0.016±0.02 – 0.124±0.06 (acenaphthylene), 0.000±0.00 – 0.040±0.05 (naphthalene), 0.060±0.08 – 0.729±1.03 (flouranthene), 0.005±0.00 – 0.083±0.11 (phenanthrene), 0.031±0.04–0.268±0.17 (1,2-benzanthracene), 0.000±0.00–0.075±0.10 (acenaphthene), 0.026±0.03 0.101±0.04 (benzo flouranthene), 0.004±0.00 – 0.142±0.06 (benzo pyrene), 0.000±0.00 – 0.128±0.04 (pyrene), 0.000±0.00 – 0.059±0.06 (perylene), 0.000±0.00 – 0.000±0.00 (dibenzy), 0.000±0.00 – 0.076±0.11 (flourene), 0.000±0.00 – 0.151±0.12 (xylene), 0.000±0.00 – 0.002±0.00 (anthracene). Flouranthene and 1,2-benzanthracene concentrations were the most frequently found PAHs in all samples. These PAHs have four rings (high molecular weight PAHs). This suggests that the river water includes highly strong, non-biodegradable mutagens and carcinogens that are harmful to human health when consumed. The PPI values discovered from the examination of the water samples are in the following order: sample-002 > sample-005 > sample-003 > sample-004 > sample-001.