Pain in the left side of the waist of women may have the following causes: first, kidney disease, when the kidney tumor, inflammation, cysts, stones, can appear in the left side of the waist pain, to carry out the relevant kidney CT, nuclear magnetic or ultrasound examination for diagnosis, if necessary, urine tests for diagnosis. Second, lumbar muscle diseases, when the lumbar muscles have strain, can also appear in the lumbar pain, to conduct relevant tests to exclude other diseases for diagnosis. Third, tumors of the lumbar muscles, when there are benign or malignant tumors in the muscles, there can also be pain in the left side of the lumbar region, and relevant tests should be performed to make a diagnosis.