The prevalence of both obesity and asthma has risen in recent years. We sought to investigate whether obesity may be related to asthma. We undertook a retrospective medical record review of patient records at an inner-city academic asthma center. Obesity was defined as a body mass index (BMI) greater than 30. Asthma severity was defined by using the National Heart Lung and Blood Institute 1997 guidelines. Adults with a history of cigarette smoking or other lung disease were excluded. A total of 143 individuals aged 18-88 with a mean age of 43.9 met the entry criteria. There were 113 females and 30 males. Seventy-two percent of the sample was obese. The Spearman correlation coefficient showed a linear relationship between asthma severity and BMI (r = 0.40, p < 0.0001). Females with asthma were significantly more overweight than males, mean BMI 35.9 vs. 32.14, respectively (p = 0.01). The prevalence of obesity in the 13 patients on long-term oral corticosteroids was 100%. Prevalence of obesity increases with increasing asthma severity in adults. The association of asthma severity with obesity suggests that obesity may be a potentially modifiable risk factor for asthma or asthma-like symptoms.