Review of population-based studies estimates that 17% of adult asthma is attributable to workplace exposures. However, work-related asthma is often underdiagnosed. Farm-related exposures have been shown to cause or aggravate asthma among farmers. Limited information is available on the prevalence of asthma and asthma in relation to farm work among primary farm operators. Therefore, we estimated the prevalence of asthma and the proportion of asthma related to work on the farm among US primary farm operators using data from 2011 Farm and Ranch Safety Survey (FRSS). Operators were determined to have current asthma if they have ever been told by a doctor, nurse, or other health professional that they had asthma and still have asthma. Operators with current asthma were determined to have asthma related to work on the farm if they have ever been told by a doctor, nurse, or other health professional that their asthma was related to their work on the farm. The National Agricultural Statistics Service reported an estimated 2.2 million farm operations were actively farming in 2011 in the United States. Data from the 2011 FRSS found most primary farm operators were aged 40.64 years (58.2%) and males (83.6%). An estimated 5.0% of operators had current asthma. Of these, 15.1% had asthma related to work on the farm. Among operators with asthma related to work on the farm, 26.2% were located in the North, 16.7% had a second job, 41.1% managed farms with >1,000 acres, and 32.2% managed farms with a value of sales .$100,000. This study addressed the National Occupational Research Agenda surveillance goal for the Agriculture, Forestry, and Fishing sector by providing information on asthma prevalence among primary farm operators and identifying areas for future studies. These results add to the limited information about the prevalence of asthma and asthma related to work on the farm among primary farm operators. Future studies should examine potential workplace exposures associated with asthma development among primary farm operators.