In recent years, follow-on biological products (biosimilars) have received much attention from both the biotechnology industry and the regulatory agencies, especially after the passage of the 2010 healthcare reform bill. Unlike the traditional small-molecule drug products, the development of biological products is not only more complicated but also sensitive to small changes (both mean and variation) in procedure/environment during the manufacturing process because of some fundamental differences between drug products and biological products. A small change will have an impact on the quality of the product and consequently the treatment effect. Thus, in addition to the assessment of biosimilarity in average, it was suggested that biosimilarity in variability between biological products should be assessed. In this article, we propose an adapted F-test for homogeneity of variances to assess biosimilarity in variability. We study the performance and concordance of the proposed adapted F-test and compare it with probability-based method by extensive Monte Carlo simulations. Copyright © 2012 John Wiley & Sons, Ltd.