BACKGROUND: The aim of the present study is to describe the clinical correlates of hypotension and its associated outcomes in patients with acute organophosphorus poisoning (AOPP). METHODS: In this retrospective cohort study, we analyzed data pertaining to 871 patients with AOPP who were treated at two hospitals. Data from hypotensive and non-hypotensive patients were compared to identify clinical correlates of hypotension. We also evaluated the association between clinical parameters (including hypotension) and in-hospital mortality. RESULTS: The incidence of hypotension in AOPP patients was 16.4％. Hypotensive patients showed significantly higher in-hospital mortality (1.1％ vs. 39.9％, P<0.001). Advanced age (odds ratio [OR] 1.25, 95％ confidence interval [CI] 1.08-1.44), history of diabetes (OR 2.65, 95％ CI 1.14-5.96), and increased white blood cell count (OR 1.06, 95％ CI 1.03-1.09), plasma cholinesterase (OR 0.91, 95％ CI 0.84-0.94), plasma albumin (OR 0.88, 95％ CI 0.85-0.92), serum amylase (OR 1.01, 95％ CI 1.01-1.02), and blood pH (OR 0.64, 95％ CI 0.54-0.75) were significantly associated with hypotension. After adjusting for potential confounders, hypotension was associated with increased in-hospital mortality (hazard ratio 8.77-37.06, depending on the controlled variables). CONCLUSIONS: Hypotension is a common complication of AOPP and is associated with increased in-hospital mortality. Advanced age, history of diabetes, and changes in laboratory parameters were associated with hypotension in AOPP patients.