BACKGROUND: The prevalence of medically compromised patients seeking dental care varies across different countries. There have been no published reports about this clinical topic in Mexico. OBJECTIVES: We aimed to determine the prevalence of systemic diseases in patients who attended the Diagnostic Clinic at the Faculty of Dentistry of the Autonomous University of San Luis Potosí in Mexico from 2011 to 2019. MATERIAL AND METHODS: The study was based on the analysis of electronic files from 82,363 medically compromised patients registered in the clinic during the aforementioned period. Each file was entered into an electronic medical record using the Microsoft Visual Basic.NET software and completed by an undergraduate student based on a personal interview. The collected information was then analyzed with the use of Stata 14 statistical package. RESULTS: The global prevalence of medically compromised patients among the patient population was 39.1%. Comorbidities were more prevalent in female patients (71.9%) compared to male patients (28.1%). The most prevalent diseases in adults were gastrointestinal diseases (16.5%), arterial hypertension (14.1%) and diabetes mellitus (8.6%). CONCLUSIONS: In a third of the registered cases, an associated comorbidity was identified. It is therefore necessary for dental undergraduate students to receive comprehensive training during their academic formation to facilitate the timely and accurate diagnosis of systemic diseases, as part of the dental care protocol for adult patients.