Introduction: The objective was to describe social inequalities in the use of healthcare and preventive services in the Midi-Pyrénées region using health insurance databases and an ecological indicator of deprivation. Methods: The study population consisted of adult beneficiaries of the three main health insurance schemes as of December 31, 2012, totaling more than 2 million people. Ten indicators of healthcare and preventive care utilization, calculated over a 12-month period, were developed. The influence of socioeconomic status, measured by an ecological deprivation index—the European Deprivation Index (EDI)—calculated after geocoding the individual’s exact address and assigning the corresponding Iris code to that address, was analyzed after adjusting for age, sex, and exemption from copayments for chronic conditions. Results: A steady decrease in healthcare utilization—including at least one visit to a general practitioner or gynecologist per year, conservative dental care, reimbursement of optical expenses, and use of mammography and Pap smears—was observed as deprivation increased. This social gradient was reversed for the use of anxiolytics and tooth extractions. No social gradient was apparent in the population of treated diabetics, with social differences observed only for ophthalmology consultations. Discussion: A social gradient in healthcare and preventive care utilization was widely observed in the Midi-Pyrénées region. This study demonstrates that it is possible to address social health inequalities using medical-administrative databases, particularly to describe them at a fine geographic scale.