The study was planned to determine the most common nursing diagnoses according to NANDA International (NANDA-I) taxonomy and difficulties experienced in using of nursing process in COVID-19 outbreak. The sample of the descriptive cross-sectional study consisted of nurses cared for patients with COVID-19 (n = 114). Average age of nurses is 26.86 ± 6.68. Commonly determined nursing diagnoses according to NANDA-I taxonomy in patients with COVID-19 were imbalanced nutrition (66.7%), impaired gas exchange (40.4%), insomnia (21.1%), acute confusion (31.6%), hopelessness (96.5%), difficulty playing caregiver (84.2%), anxiety (38.6%) willingness to strengthen religious bond (71.9%), risk for infection (64.9%), nausea (49.1%). Twenty-four-years old and younger, high school graduates, caring for intubated patients, and those who stated that they did not use nursing diagnosis had more difficulty in using nursing process (<0.05). The use of nursing diagnoses and process for patients with COVID-19 is extremely important in ensuring individual and qualified nursing care.