The present invention concerns methods and compositions for diagnosing and/or treating vascular diseases including cancer, cardiac diseases, vascular diseases of the eye, and inflammatory diseases. The methods involve measuring the levels of one or multiple miRNAs in patient samples and using the test results to diagnose and/or predict an optimal treatment regimen for the patient. Compositions described in the invention include nucleic acids that function as miRNAs or miRNA inhibitors that can be introduced to a patient to reduce or increase vascularization as needed.