The impact of environmental chemical exposure on blood pressure (BP) is well-established. However, the relationship between secondhand smoke exposure (SHSE) and mortality in hypertensive patients in the general population remains unclear.This cohort study included US adults in the National Health and Nutrition Examination Survey from 2007 to 2018. All-cause mortality and cause-specific mortality outcomes were determined by associating them with the National Death Index records. Cox proportional risk models were used to estimate hazard ratios (HRs) for all-cause mortality and cardiovascular disease (CVD) mortality, and 95% confidence intervals (CIs) for SHSE. The cohort included 10,760 adult participants. The mean serum cotinine level was 0.024 ng/mL. During a mean follow-up period of 76.9 months, there were 1729 deaths, including 469 cardiovascular disease deaths recorded. After adjusting for lifestyle factors, BMI, hypertension duration, medication use, and chronic disease presence, the highest SHSE was significantly associated with higher all-cause and CVD mortality.This study demonstrates that higher SHSE is significantly associated with higher all-cause mortality and CVD mortality. Further research is necessary to elucidate the underlying mechanisms.Copyright © 2024 The Italian Diabetes Society, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.