This protocol is intended as a guideline for the quantification of total miRNAs, from serum and plasma samples, using the Qubit® microRNA Assay Kit and the Qubit® 2.0 Fluorometer. This method have been able to reproducibly quantify small RNA in pure samples at levels as low as 0.5 ng in the assay tube following. The assay detects all types of small RNA, including microRNA and siRNA, both single stranded and double stranded. Samples for quantification are the final product of purification procedures, stored in 1,5ml microtubes at -80ºC. The aim of this protocol is to provide the exact amount of each sample to standardize the dilution for RT-rtPCR protocol.