Background: Geriatric patients with inadequate health literacy less careful of medication adherence impact. Aim: Assess health literacy and medication adherence among geriatric patients. Design: A descriptive research design was utilized in this study. Setting: The study was conducted at the geriatric outpatient clinic of the specialized Medical Hospital at Mansoura University and the outpatient clinic of Mansoura Specialized Hospital affiliated to Ministry of Health & Population, Dakahlia Governorate. Subjects: A purposive sample of 255 geriatric patients who met the inclusion criteria were enrolled in the study. Tools: Three tools were used to collect data; Demographic, Health Related Data and Activities of geriatric patients Interview Questionnaire Sheet, European Health Literacy Survey Questionnaire and 8-items Morisky Medication Adherence Scale. Key results: Limited health literacy (inadequate and problematic) was prevailing among 67.5% of the studied geriatric patients as well as, low medication adherence level was common among 78% of the studied geriatric patients. Conclusion: There was a highly statistically significant positive correlation between health literacy and medication adherence among geriatric patients as sufficient health literacy is associated with higher medication adherence in geriatric patients. Recommendation: Adopting multidimensional approaches aimed to improve health outcomes of geriatric patients as supporting medication adherence, improving health literacy skills, and maintaining a close nurse–patient relationship with effective communication. Also, further studies and research are needed about health literacy, medication adherence and the impact of health literacy on medication adherence among larger numbers of geriatric patients in different demographic areas in Egypt.