Reliability and accuracy of real-time quantitative PCR results depend on the use of housekeeping genes which must be constitutively expressed thorough the samples of the study. In the present work, we tested the expression stability of six candidate housekeeping genes (Actb, Rn18s, Gapdh, Hprt1, Sdha and B2m) considering sex, age, muscle-type and neurodegeneration or denervation status in mouse muscle satellite cells. Their expression varied under all variables tested; therefore the ranking of the most suitable genes for the normalization is modified depending on the factors included in the analysis, especially the age of the donor. Moreover, we describe the unsuitability of Rn18s in analysis comprising samples of different ages. On the other hand, we demonstrate that the use of the two best genes in each case is enough to obtain a reliable normalization factor. In this work, we give a broad information of the best housekeeping genes in mouse myogenic cells depending on the variables included in the experimental design. (C) 2011 Elsevier Inc. All rights reserved.