Secondhand tobacco smoke (SHS) exposure is a well-established risk factor for several diseases in adults. Despite the evidence that active tobacco smoke is harmful for the muscles, the association between SHS and muscle strength is still uncertain.We analyzed data from 5390 nonsmoking U.S. adults aged >30 years who participated in the National Health and Nutrition Examination Survey (NHANES) 2011-2014. Exposure to SHS was assessed with serum cotinine concentrations. Grip strength was measured using a Takei digital handgrip dynamometer, and combined grip strength was calculated as the sum of the largest reading from each hand. Median (interquartile range) serum cotinine and grip strength were 0.015 ng/mL (IQR 0.011-0.36) and 65.5 kg (IQR 53.4-86.4), respectively. After adjusting for sociodemographic, anthropometric, health-related behavioral, and clinical risk factors, the highest (0.047-9.9 ng/mL) vs lowest (≤0.011 ng/mL) quartile of serum cotinine was associated with a reduction in combined grip strength of 1.41 kg (95%CI: -2.58, -0.24), p-trend=0.02. These results were consistent across socio-demographic and clinical subgroups. In the US nonsmoking adult population, even low levels of exposure to passive smoking were associated with decreased grip strength. Despite great achievements in tobacco control, extending public health interventions to reduce SHS exposure is still needed.