ObjectiveTo evaluate the measurement capability of laboratories of radiological health technical service institutions in Shanghai for determining gross alpha and gross beta radioactivity in water. MethodsAll local laboratories with operational scope covering gross alpha and gross beta radioactivity measurement (hereinafter referred to as "participating laboratories") were organized to undertake a proficiency test. Each participating laboratory measured the gross α and gross β radioactivity concentrations in the proficiency testing water samples using the thick source method specified in GB/T 5750.13‒2023 Standard Examination Methods for Drinking Water—Part 13: Radioactive Indicators. Based on GB/T 28043‒2019 Statistical Methods for Proficiency Testing Using Interlaboratory Comparisons, the measurement results of all participating laboratories were statistically evaluated. The inter-laboratory comparison results for 2023‒2024 were uniformly assessed using z-scores: laboratories with |z| ≤2.00 for both gross α and gross β were rated as satisfactory (pass), and those with |z| ≤0.50 for both gross α and gross β and with the sum of the comprehensive score and the Q value ≥95 points were rated as excellent. ResultsIn 2023, 15 laboratories participated in the provincial inter-laboratory comparison, with a pass rate of 86.67% and none rated as excellent. In 2024, 19 laboratories participated, with a pass rate of 100% and 21.05% rated as excellent. ConclusionCompared with 2023, both the pass rate and the excellence rate in 2024 improved significantly, indicating that the measurement capability of the participating laboratories for gross alpha and gross beta radioactivity in water has been effectively enhanced. Improving the testing capabilities of laboratories in technical service institutions strengthens preparedness for future public health emergencies.