The present study focuses on the micro ribosomal nucleic acid 155 since this molecule represents a typical multifunctional micro ribosomal nucleic acid. To date, increased evidence points out that micro ribosomal nucleic acid 155 is involved in numerous biological processes including haematopoiesis, inflammation and immunity. Deregulation of micro ribosomal nucleic acid 155 has been found to be associated with different kinds of cancer, cardiovascular diseases and viral infections. Since investigation on the functional activity of micro ribosomal nucleic acid 155 started a few years ago, it is reasonable to predict that many other functions will be uncovered in the near future.