Slipped capital femoral epiphysis (SCFE) is the most common hip disorder of adolescents and is known to be strongly associated with obesity. The use of Body Mass Index (BMI) as an assessment of obesity has been shown to be a very efficient technique. The Centers for Disease Control & Prevention has recently developed BMI-for-age percentile growth charts that have been shown to effectively evaluate obesity in the pediatric population. In the current study, the investigators provide a retrospective review, looking at the association between SCFE and obesity based on BMI. One hundred six subjects with radiographically diagnosed SCFE were compared with 46 controls without radiographic evidence of SCFE. In the SCFE group, 81.1% of individuals had a BMI above the 95th percentile; for the control group, the corresponding figure was only 41.3% (P < 0.0001). Multiple linear regression analysis controlling both for sex and age confirmed an equally significant difference (P < 0.0001) between SCFE patients and controls with regard to BMI. Based on pediatric obesity criteria designating a weight above the 95th percentile as obese and a weight between the 85th and 95th percentile as "at risk" for obesity, clinicians can use BMI to define obesity, a highly modifiable risk factor for SCFE. Early intervention and lifestyle modifications may reduce the incidence of not only SCFE but other illnesses related to obesity as well.