Although portable x-ray fluorescence (XRF) technology is widely accepted for environmental use in field screening test regarding the analytical approach, it needs to be evaluated with sufficient data and meet its performance characteristics to be employable for decision making purposes. Usually, for an XRF sample, the most interesting query is: How reliable is the XRF technique in detecting different targeted metals in soil? This study presents pairwise comparisons between the XRF and inductively coupled plasma atomic emission spectrometer (ICP-AES) results for individual elements of Ni, Cu, Zn, Pb, Cd, Cr, Hg, and As. The portable XRF analyzer was used to estimate the concentration levels of eight heavy metal elements, and then pairwise comparisons were made between the XRF and ICP-AES results. Results presented in this paper suggest that the use of XRF testing is highly reliable as a screening technique for the first sample group of metal element (Pb, Zn, Ni, and Cu) concentrations well in excess of the pollution threshold limits (PTLs). The order of reliability of the XRF measurements is Pb > Zn > Ni > Cu, and their relative proximity (RP) ranges from 85%-35%. In contrast, the results of another group of metal elements that include Hg, Cd, Cr, and As show poor correlation. Their RP ranges from 25%-2.3%.Keywords: x-ray fluorescence (XRF), heavy metal, inductively coupled plasma atomic emission spectrometer (ICP-AES), soil pollution, relative proximityDuring the year of 1970, industry was booming and great quantities of industrial wastes were dumped along the Erren River in Taiwan. Electronic waste recyclers and metal smelters accounted for approximately 80% of all illegal dumping activity along the Erren River. Since 2001, restoration of the Erren River has been ongoing and the Environmental Protection Agency (EPA) of Taiwan has spent NT$ 50-60 million (Taiwan dollars) to clean up sites along the river even though funding for the clean-up effort has been difficult to secure. In 2007, a huge amount of hazardous contaminants of electronic wastes, which included stripped electronic circuit boards, plastic-coated metals, and unknown composites were found embedded in the subsurface soil on both sides of the riverbanks during a riverbank construction project along a 3-kilometer stretch down-