Health literacy is an important skill and capacity that affects individuals' ability to make decisions about their health and manage their health. It is associated with low health literacy, unnecessary outpatient clinic visits, high health expenditures, late diagnosis, and risky health behaviors. This research was conducted with 373 patients who applied to the Chest Diseases outpatient clinic of a training and research hospital in Istanbul. 20.4% (n=76) of the participants had low health literacy and 49.9% (n=186) had middle health literacy. According to the gender of the patients, while there was no significant difference in access to treatment health services, total score and self-efficacy subscale dimensions, the median of the health promotion subscale dimension was higher in women than in men and was found to be statistically significant. Statistically significant differences were found in access to treatment health services, health protection development, total score and self-efficacy subscale dimensions according to the educational status of the patients. Statistically significant differences were found in access to therapeutic health services, health promotion, total score and self-efficacy subscale dimensions according to the occupation of the patients. Health literacy level was found to be low in one out of every four patients. Gender, educational status and occupation were found to be effective on health literacy level.