High-performance capillary electrophoresis (HPCE) is shown to be useful for analysis of interleukin-2 (IL-2) in its native state under non-reducing conditions. The results obtained were compared with those from analysis of IL-2 by protein blotting after sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) under denaturing and reducing conditions. In addition, resolution of the different glycosylated and non-glycosylated natural IL-2 species was achieved by HPCE. The HPCE electropherogram of native IL-2 could easily generate quantitative amounts of the different naturally occurring IL-2 species. For HPCE of IL-2 run times of less than 10 min are sufficient, and only extremely small amounts of IL-2 are needed. In this report, human IL-2 expressed in bacteria has been analysed by HPCE and the existence of two recombinant IL-2 forms was demonstrated.