Adherence to non-vitamin K antagonist oral anticoagulants (NOACs) is an important factor for ensuring efficacy and safety in nonvalvular atrial fibrillation (NVAF). There are controversial results regarding NOAC adherence in real-world data and there are no data about NOAC adherence in Turkish population. This study investigated the NOAC adherence based on self-report, factors affecting nonadherence, and the relation of the adherence level with efficacy and safety outcomes. This multicenter cross-sectional study included 2738 patients (59% female) using NOAC (dabigatran, apixaban, and rivaroxaban) due to NVAF for more than 3 months with >30 days of supply between September 1, 2015, and February 28, 2016. To measure the adherence level, an 8-item Morisky Medication Adherence Scale was used. The mean age of the patients was 70 +/- 10 years. Of the 2738 patients, 44% were receiving dabigatran, 38% rivaroxaban, and 18% apixaban. A total of 630 (23%) patients had high medication adherence, 712 (26%) moderate adherence, and 1396 (51%) low adherence. Nonadherence had related to stroke (5.6% vs 2.5%, P < .001) and minor (21.2% vs 11.1%, P < .001) and major (6.1% vs 3.7%, P = .004) bleeding rates. The adherence to NOAC was found to be quite low in Turkey. Nonadherence is associated with bleeding and thromboembolic cardiovascular events. Age, taking NOAC twice a day, and the additional noncardiac diseases, depression, and dementia were the independent factors affecting poor medication adherence.