DNA fragments of 1 to 10 kbp in length were separated by capillary electrophoresis (CE), using poly(ethylene oxide) (PEO) solutions in the presence of electroosmotic flow. The technique requires filling the capillary with the polymer solution by means of electroosmotic flow (EOF). Separation times of 6-7 min in PEO solutions ranging from 0.3 to 8 x 10(6) Mr at 375 V/cm were sufficient to separate the 11 components of the dsDNA ladder (0.5 to 10 kbp) by size. The migration behavior of the double-stranded (ds)DNA fragments, interpreted by "Ferguson plot analysis", in the system is indistinguishable from that previously reported for capillary zone electrophoresis (CZE) in a polyacrylamide solution without EOF. Potential advantages of conducting CZE using polymer solutions in the presence of EOF are: (i) Possibility of long migration times on short columns; (ii) possibility of introducing relatively viscous, high Mr polymer solutions into narrow capillaries; (iii) possibility of establishing polymer concentration gradients in capillaries; (iv) possibility of concentrating the starting zone by balancing electrophoretic migration and electroosmotic transport.