Mantle cell lymphoma is a blood cancer. Patients with this disease live an average of 3 years. Some patients do well with simple treatments but most patients are treated with strong chemotherapy that can have many side effects, yet they are still not cured. Current tests may be helpful but are not good predictors of survival, meaning new markers need to be studied. Abnormal amounts of molecules known as microRNAs can cause cancer. We will study whether the amount of microRNAs in mantle cell lymphoma is different from normal, and whether microRNAs can predict patient survival. If a set of microRNAs can help divide patients into different groups, for different therapies, we can identify patients that may benefit from strong chemotherapy, and those that may do well with simpler treatment. We expect that amounts and types of microRNAs in mantle cell lymphoma will predict patient survival, and that certain microRNAs are involved in the development of more aggressive forms of mantle cell lymphoma.