This study was conducted to investigate potentially toxic elements (PTE) contamination and health risk of groundwater in selected municipal solid waste (MSW) disposal sites of Khyber Pakhtunkhwa, Pakistan, where a large number of local communities are living near the disposal sites. A total of 30 surface and groundwater samples were collected from MSW disposal sites in Abbottabad, Bannu, and Peshawar. The collected samples were analyzed for physicochemical parameters such as pH, electrical conductivity (EC), and PTE, including cadmium (Cd), manganese (Mn), copper (Cu), nickel (Ni), and lead (Pb). Results indicated that mean pH values (7.05±0.26, 7.14±0.17, and 6.98±0.12) were found within the acceptable limits (6.5-8.5) specified by National Environmental Quality Standards (NEQS) and World Health Organization (WHO). Mean concentrations of PTE were within NEQS and WHO limits, except for nickel (Ni) (1.88±0.15, 0.52±0.07, and 2.02±0.12 mg L^-1), which exceeded the NEQS and WHO limit of 0.02 mg L^-1 in all samples. Similarly, manganese (Mn) (0.56±0.07 mg L^-1) exceeded the limit set by NEQS and WHO (0.5 mg L^-1) in the groundwater samples of the Bannu MSW disposal site. Multivariate analysis indicated that the PTE contamination of the groundwater of the selected MSW disposal sites was anthropogenic. The pollution index (PI) values (PI ≥ 100) of Mn and Ni indicated very high pollution at individual levels, while collectively, based on heavy metals pollution index (HPI) values (HPI ≥ 200), the groundwater of all the selected MSW disposal sites was found highly polluted. Whereas the hazard index (HI) values (HI ≥ 5) suggested adverse health effects. It was concluded that the groundwater of all the MSW disposal sites was highly polluted with heavy metals, particularly Ni and Mn, thus posing a high health risk to local communities living near the MSW disposal sites.