There are many reasons for unsmooth nails with vertical lines, such as endocrine disorders, malnutrition, fungal infections and so on. 1. Endocrine imbalance: recent irregularities in life and diet, lack of sleep, fatigue, and mental stress may cause endocrine imbalance, leading to unsmooth nails with vertical lines. 2. Nutritional deficiencies: anemia, vitamin deficiency, lack of trace elements and other nutritional deficiencies may also lead to unsmooth nails with vertical lines. 3. Fungal infections: various fungal infections of the nail plate or nail fungal disease caused by subnail tissue, may cause the surface of the nails to lose luster, uneven nails, or nail hypertrophy, the color of gray-white, gray-brown, and so on, can also lead to the nails are not smooth with vertical lines. There may be other causes for uneven nails, so it is recommended to go to the hospital for examination and treatment as prescribed by the doctor.