The inhibitory effect of serum is one of the main obstacles less in primary human myoblasts. The lower transgene to the in vivo use of cationic liposomes as a DNA delivery expression in primary cells does not appear to be a result system. We have found that a novel liposome formulation, of less DNA uptake but might result from differences in DODAC:DOPE (1:1) is totally resistant to the inhibitory intracellular trafficking of the complexes. DODAC-based effects of serum for transfection of cultured myoblasts and liposomes are unique in their resistance to serum inhibition myotubes. Transfection with a lacZ reporter gene in the and may therefore be valuable for the systemic delivery of presence of 95% fetal bovine serum gave up to 25% -genetic information to muscle and other tissues. gal-positive cells in C2C12 myoblasts and about six-fold