Osteoporosis is a chronic, progressive disease in which early diagnosis is very important. The neutrophil-to-lymphocyte ratio (NLR) and the platelet-to-lymphocyte ratio (PLR) have been reported as new predictors in inflammatory and immune diseases including osteoporosis. No studies have reported the relationship between monocyte-to-lymphocyte ratio (MLR) and osteoporosis patients.To investigated the ability of MLR to predict osteoporosis.Three hundred sixteen osteoporosis patients and 111 healthy control subjects were enrolled. Patients' laboratory and clinical characteristics were recorded. MLR, NLR, and PLR levels were calculated. The differences were compared and the diagnostic values of MLR were analyzed.There were 76 male and 105 female patients included, with a mean age of 56.57 ± 9.95 years. The levels of MLR, NLR, and PLR in osteoporosis patients were all higher than those in healthy control subjects. The area under the curve of MLR was higher than those of NLR and PLR. Multivariate linear regression analysis showed that T-score was affected by age and MLR. MLR was positively correlated with C-reactive protein, erythrocyte sedimentation rate, red blood cell distribution width, age, sex, and inversely with hemoglobin. MLR and PLR levels were significantly higher in osteoporosis patients than in osteopenia patients (P < .05).The present study shows that MLR had a higher diagnostic value for osteoporosis. MLR may be a reliable, inexpensive, and novel potential predictor of osteoporosis.