The aim of this study was to evaluate the concentrations of polycyclic aromatic hydrocarbons (PAHs) in 1168 groundwater samples of the Campania Plain (Southern Italy), taken using a municipal environmental pressure index (MIEP), and to analyze the distribution of these compounds to determine source PAHs using ratios of isomers diagnostic. Lastly, this study also aimed to estimate the potential health cancer risk in groundwaters. The data indicated that the highest concentration of PAHs was found in groundwater from Caserta Province and the contents of BghiP, Phe, and Nap were detected in the samples. The spatial distribution of these pollutants was evaluated using the Jenks method; moreover, the data indicated that incremental lifetime cancer risk ILCRingestionranged from 7.31 × 10−20to 4.96 × 10−19, while ILCRdermalranged from 4.32 × 10−11to 2.93 × 10−10. These research findings may provide information about the Campania Plain’s groundwater quality and aid in the development of preventative measures to lessen PAH contamination in groundwater.