OBJECTIVES: The US ranks first among all developed countries for obesity/overweight prevalence. Anti-obesity medications may help address this public health problem, but national utilization data for anti-obesity medications is lacking. The study objective was to examine trends in anti-obesity medication use among adults who met medical criteria (MC) and understand the extent of use of such medications among adults who did not meet MC. METHODS: A retrospective cross-sectional study was performed using the Medical Expenditure Panel Survey data from 2002-2007. The study comprised all non-pregnant adults (≥20 years of age; N=210,829,728). Meeting the MC for anti-obesity medication use for an individual was defined as having Body Mass Index (BMI) > 30 (clinically obese) or having BMI ≥ 27 with comorbidities such as hypertension, cardiovascular disease, diabetes and hyperlipidemia. Anti-obesity medications were identified from prescription medicine files using national drug codes and drug names. Proportions of anti-obesity medication users among adults who met MC were calculated for each year and logistic regression was performed to test utilization trends. Descriptive analysis was conducted to assess proportion of adults using anti-obesity medications who did not meet MC.  RESULTS: Of the adults who met MC (N=65,886,625), 0.52% were taking anti-obesity medications. Analysis of multiyear data showed no statistically significant trend (p-value = 0.25) in anti-obesity medication use among adults who met MC from 2002 to 2007. Of all US adults who were taking anti-obesity medications (N=542,297), 31.98% did not meet MC for use.  CONCLUSIONS: Less than one percent of eligible adults used anti-obesity drugs in each year and anti-obesity medication use did not change from 2002 to 2007. Almost one third of anti-obesity medication users did not meet MC. Given the associated side-effects for these medications, further research is needed to understand the use of anti-obesity medications among adults who do not meet MC.