OBJECTIVES: The goal of the study is to compare total healthcare cost and health resource use (HRU) of utilizers and non-utilizers of onsite clinics provided by Crossover Health. The popularity of these clinics has been increasing as more employers are “opting out” of the traditional healthcare system but their outcomes have not yet been assessed METHODS: We retrospectively examined medical claims from 2 large employers, (EMP1;EMP2), whose employees had access to Crossover Health onsite clinics. Patients who were continuously eligible for at least 6 months with at least one claim were evaluated for inclusion in one of two cohorts: Non-users of onsite health clinics and Engaged(at least 2 visits or >=50% of their visits to an onsite health clinic).  Mean annualized costs and HRU for the groups was evaluated by multiple regression models controlling for demographics and comorbidities.   RESULTS: A total of 5,801 patients(3,476 non-users, 2,325 engaged) were evaluated for EMP1 and 2,267 patients(1,709 non users, 558 engaged) were evaluated for EMP2. When HRU was evaluated, EMP1 engaged patients had significantly fewer inpatient and outpatient visits but significantly greater office visits (p<0.0001). EMP2 engaged patients had significantly fewer ER visits & significantly greater inpatient and office visits vs. non-users (p<0.0001). Mean (SD) annual costs per person were significantly lower (p<0.001) for engaged vs. non-users for both groups: $2,854($16,936) vs $3,137($14,103) for EMP1 and $2,229($8,097) vs $3,321($13,921) for EMP2. On average, engaged patients spent $0.72(EMP1) and $0.67(EMP2) for every dollar spent by non-users. For both employers, inpatient, outpatient and ER costs trended lower for engaged vs. non-users CONCLUSIONS: This research supports the hypothesis that comprehensive patient centric primary care leads to significantly lower rates of resource utilization and costs. Engaged users of onsite health clinics have lower total health care costs with a savings of 28 to 33 cents for each dollar spent by non-users.