Medical fitness programming in an exercise facility closely coordinated with a medical and physical therapy practice may be an effective means to introduce exercise to an at-risk population. PURPOSE: To assess the effectiveness of a structured exercise program on reducing risk factors in a population of at-risk patients administered at a Medically Oriented Gym (MOG) located in proximity to a primary care practice. METHODS: Participants (n=102) were a convenience sample recruited by a physician (RJ) based on existing comorbidities. Following three enrollment periods, 62 participants (30 female) completed the 12 month exercise intervention with assessments for weight, BMI, waist circumference, body composition and sub-maximal VO2 at baseline and each subsequent three months. Attendance to exercise sessions was also recorded for each quarter. RESULTS: There were no significant differences between those that completed and drop outs for any baseline measures with an overall patient compliance rate of 58.8%. In those that completed the 12 month program there were significant decreases in body weight (4.02 kg, p=0.001), BMI (1.52, p<0.001), waist circumference (4.88 cm, p<0.001) and percent body fat (1.25%, p<0.001) and a significant increase in sub-max VO2 (7.19 ml/kg/min, p<0.001). Significant changes occurred between entry and 6 months in weight, between entry and 3 months in percent body fat and between entry and both 3 and 6 months in BMI, waist circumference, and sub-max VO2. There was no significant change for any measure following the 6 month assessment. While there was no difference in MOG attendance between the first and second quarters (21.6 and 22.7 average visits respectively, p=0.4), attendance significantly dropped from the second to third quarter (18.5 visits, p<0.001) and significantly decreased further across the fourth quarter (15.48 visits, p=0.02). The loss of statistically significant improvement in clinical outcomes corresponded to the decrease in attendance after 6 months. CONCLUSION: Participation in an exercise intervention at a MOG facility can significantly reduce risk factors associated with obesity and chronic disease. This improvement is related to attendance in exercise sessions where both participation and significant improvements appear to decrease after 6 months.