Multigene delivery systems for heterologous multiprotein expression in mammalian cells are a key technology in contemporary biological research. Multiprotein expression is essential for a variety of applications, including multiparameter analysis of living cells in vitro, changing the fate of stem cells, or production of multiprotein complexes for structural biology. Depending on the application, these expression systems have to fulfill different requirements. For some applications, homogenous expression in all cells with defined stoichiometry is necessary, whereas other applications need long term expression or require that the proteins are not modified at the N- and C-terminus. Here we summarize available multiprotein expression systems and discuss their advantages and disadvantages.