The present invention provides compositions comprising mRNA molecules encapsulated within lipid particles. The lipid particles comprise a cationic lipid, a non-cationic lipid, and an mRNA molecule that is encapsulated within the lipid particle. The compositions are useful, for example, to introduce the mRNA molecules into a human subject where they are translated to produce a polypeptide that functions to ameliorate one or more symptoms of a disease. The invention also provides cationic lipids that are useful for preparing the compositions of the invention.
