Abstract: In this study, we measured directly through the technique of micromanipulation by micropipette the viscosity of mouse muscle cells modified by transfection with the αβ-crystalline in order to highlight the role played by the changes in the cytoskeleton. Two vectors were used, the αβ-crystalline of wild type and R129G αβ-crystalline mutant. The medium and intrinsic cell viscosities were determined and compared. For this purpose, two populations of muscle cell clones were used: WT5, WT6 for cells transfected with the αβ-crystalline of wild type and Mut9, Mut11 for cells transfected with R129G αβ-crystalline mutant. There is a difference between the medium and intrinsic viscosities of these different types of muscle cells of mice.