A 5-mm ground glass nodule has a high likelihood of being benign and some risk of being malignant. If the nodule is benign, it is not serious; if it is malignant, such as lung cancer, it is more serious. Lung nodules may be caused by benign diseases such as pneumonia, misshapen tumors, and sarcoidosis, or by malignant tumors such as bronchopulmonary cancer and lung metastases. The risk of malignancy in lung nodules is related to the size, density, and morphology of the nodule. The probability of malignant lesions in 5mm lung nodules is low, around 1%, and generally the nodules will have a malignant risk of around 15% until they are >8mm. Frosted glass nodules are cloudy, slightly dense shadows on chest CT that can be caused by inflammatory exudates from the lungs or by lung cancer. Milled glass nodules include mixed milled glass nodules and pure milled glass nodules, with mixed nodules having a high risk of malignancy and pure milled glass nodules nodules having a lower risk of malignancy. Generally, 5mm ground-glass nodules can be followed up with repeat CT to observe the changes of the lesion, and puncture and surgery are feasible when the lesion is enlarged or the solid component is increased. It is recommended that patients consult with specialists, analyze the lesions with other characteristics such as morphology, and follow the doctor’s instructions for further examination and treatment.