Provided herein are methods for generating human induced pluripotent stem cells free from genomic integration of exogenous transgenes by transfecting into nucleated blood cells one or more DNA expression vectors (e.g., plasmid vectors) that do not contain a mammalian origin of replication, and encode and permit expression of one or more reprogramming factors (e.g., Oct4, Sox2, Klf4, and c-Myc). Also provided herein are the integration-free human induced pluripotent stem cells obtained by the methods described herein.