Chest pain is a common reason for admission to hospital and little is known regarding 30-day unplanned readmissions after an admission with a primary discharge diagnosis of nonspecific chest pain. We analyzed patients with a primary diagnosis of nonspecific chest pain in the Nationwide Readmission Database who were admitted in 2010 to 2014. Rates, causes, and predictors of 30-day unplanned readmissions were determined. A total of 1,842,270 patients had a diagnosis of nonspecific chest pain. The 30-day unplanned readmission rate was 8.6%. From 2010 to 2014, there was an increase in 30-day unplanned readmissions from 8.1% to 9.5%. The majority of 30-day unplanned readmissions were for noncardiac reasons (73.4%). The 3 most prevalent noncardiac causes for readmissions were neuropsychiatric (10.9%), gastrointestinal (10.5%), and infections (9.9%), while the 3 most prevalent cardiac causes were coronary artery disease including angina (8.4%), arrhythmias (6.6%), and heart failure 5.5%. The strongest predictors of readmission were alcohol misuse ([OR] odds ratio 1.74 95% [CI] confidence interval 1.66-1.81), renal failure (OR 1.82 95%CI 1.76-1.87), cancer (OR 2.40 95%CI 2.27-2.53), discharge to a nursing home (OR 2.26 95%CI 2.18-2.34), and discharge against medical advice (OR 1.94 95%CI 1.86-2.02). The rate of 30-day unplanned readmission was 6.1% among those who received any test compared to 9.3% in those who did not receive any test. Rates of early unplanned readmissions occur following 1 in 12 admissions for nonspecific chest pain with noncardiac causes being the most common reason. Patients who receive a cardiovascular investigation appear to have fewer unplanned readmissions.