What causes pain under the ribs on the left side?

Left Upper Abd pain: Causes of left upper abdominal pain include but are not limited to: angina, heart attack, pneumonia, injury, enlarged spleen, ruptured spleen, pancreatitis, infection / abscess of the spleen, renal infection or stone, aortic aneurysm, cancer, shingles and obstipation. It is best to have chronic abdominal pain evaluated. Severe abdominal pain warrants emergent evaluation.