The authors evaluated the Nucleofector technology as an efficient non-viral transfection method for human monocytic cells compared to standard electroporation. The commonly used monocytic cell lines U937 and THP-1 were nucleofected with either an eGFP expression plasmid or eGFP encoding mRNA. The authors demonstrated that nucleofection is superior to standard electroporation. Nucleofection yielded up to 80% transfection efficiency. Compared to standard electroporation efficiency for DNA transfection was improved by ~50% and 30% for U937 and THP-1, respectively. Also the transfer efficiency of eGFP-specific mRNA after nucleofection increased with approximately 20% compared to standard electroporation. Western blotting of protein lysates from eGFP transfected cells showed detectable eGFP expression as early as 2 hours after nucleofection. The initiation of cell death was low (2.5-fold increase of propidium iodide incorporation of DNA nucleofected cells versus non-transfected cells), or even absent (in case of mRNA nucleofection).