To improve the detection sensitivity of cationic analytes with simple experimental procedures in microchip electrophoresis (MCE), large-volume sample stacking with an electroosmotic flow (EOF) pump (LVSEP) was performed in polymer-coated microchannels. At first, cationic polybrene (PB) was employed as the coating polymer to reverse the EOF. In the LVSEP analyses, however, the PB-coated microchannel gave insufficient enrichments and broader peaks for cationic standard dyes. By the application of neutral poly(vinyl alcohol) and cationic poly(allylamine) mixture-coating, on the other hand, good enrichments of histamine were achieved by LVSEP with a sensitive enhancement factor of 120.