Abstract: A method is disclosed for determining prognosis for a patient suffering from follicular lymphoma, that determines the amount of miR-31 in a biological sample taken from the body of the patient, and assigns the patient to a prognostic group based on the determined amount of miR-31, wherein the prognostic groups and the threshold values for assignment to the prognostic groups are obtained by analyzing the amount of miR-31 in biological samples of patients with known prognosis. In the biological sample taken from the patient, the miR-31 expression may be determined along with the expression of an endogenous control, which is a small nuclear RNA or stably expressed miRNA, and, in case of absolute quantification, the expression of synthetic standards of these miRNAs and endogenous controls of known number of molecules are determined. The method allows the assignment of patients to prognostic groups by determining miR-31 expression.