Arsenic is a known environmental chemical hazard in shallow groundwaters of Cambodia and is increasingly recognised as a major problem for public health. Notwithstanding this, accurate arsenic data are not available for many wells in potentially arsenic-prone areas, particularly around the Tonle Sap Great Lake (TSL) and in the coastal provinces (CP). We present here new data for shallow groundwater (16–120-m depth) arsenic in the TSL and CP regions as well as an improved regression-kriging (RK) based groundwater arsenic hazard map for the whole country. High arsenic levels (up to 100 µg L–1) were found in shallow groundwaters from the TSL and CP regions of Cambodia, but despite strong compositional similarities (near neutral, reducing, Na-Mg-Ca-HCO3 dominated) with high arsenic level groundwaters near the Mekong and Bassac rivers, groundwater arsenic levels in both the TSL and CP regions were most commonly low (interquartile range 0.09–1.2 µg L–1). The RK geostatistical model was highly successful, accounting for over 50 % of the observed variation in arsenic concentrations countrywide and represents a potentially useful tool for policymakers and those responsible and with the interest and authority to prepare arsenic mitigation and safe water supply plans.