Wavy lines on toenails may be caused by nail dystrophy, onychomycosis or other reasons, and patients are advised to go to the hospital in time to clarify the causes. 1. Nail dystrophy: the common cause is psoriasis, nail lichen planus, eczema and other skin diseases, tumor, anemia, inflammation, etc. may also lead to nail dystrophy. It can be manifested as the central depression of the toenail surrounded by bulging, roughness or whitening, thickening and so on, and sometimes there can be the symptom of wavy lines on the toenail. 2. ringworm of the nail: ringworm of the nail is a lesion caused by dermatophytes invading the nail plate and the subnail tissues. Clinical symptoms include cloudy toenails, thickening, separation, discoloration, atrophy, shedding, buckling, and surface unevenness, etc., and the symptoms of wavy lines on the toe nails can also appear. 3. Other causes: other nail fungi such as yeast, molds and other nail fungi invade the nail plate or subnail tissues and may lead to wavy toenails. Wavy toenails may also be caused by other reasons, it is recommended to go to the hospital in time to get a clear diagnosis, so as not to delay the condition.