Objective: The purpose of this study was to determine the adult immunization status and influencing factors in people aged 65 years and over registered in a family health center in Mersin. Methods: The research was conducted in a total of 260 people aged 65 years and over who were treated in a family health center in Mersin. A questionnaire consisting of 28 items was administered by conducting a face-to-face interview with the participants. Obtained data were analyzed using the SPSS package program. Results: It was determined that 72.3% of the participants were in the age range of 65-74 years, 55.4% were females, 65.7% were primary school graduates, 65% were married, 95% were unemployed, 48.8% were retired, 20.8% lived alone, 49.2% had an income of 1.000 TL or less, 77.3% had a chronic disease, 83.1% continuously used medications, and 82.6% had a cardiovascular disease. Among the participants, 30.4% were vaccinated, and among those, 28.1% were administered the flu vaccine, 4.2% the pneumococcal vaccine, and 3.1% the tetanus vaccine. The reasons for vaccination and their rates are as follows: having penetrating injuries (46.8%), medical advice (39.2%), obligation before a pilgrimage (10.1%), a pharmacist's recommendation, and a wound from animal bites or a recommendation from their relatives (1.3%). Majority of those with a chronic disease and continuous use of medication had a high rate of vaccination (p>0.05). Further, 54.4% of male participants aged 65 years and over were administered vaccines. In total, 59.7% of the female participants, 79% of who were in the age range of 65-74 years, 49.7% of who were housewives, and 52.5% of who had an income of 1.000 TL or less were not administered any vaccine. Conclusion: The rate of adult immunization was low in people aged 65 years and over, and the adult immunization rate was affected by variables such as age, sex, educational background, and occupation