Abstract: Main-effect and epistatic QTLs (Quantitative trait locus) for plant height components (lengths of panicle,first internode,second internode,and so on) in rice were investigated by using a doubled-haploid population derived from the F₁ hybrid of a cross between an indica cultivar and a japonica cultivar.All plant height components exhibited continuous variations and normal distributions.The correlation between adjacent plant height components was positively significant while the significance of the correlation between non-adjacent plant height components was less.QTL mapping detected 6 QTLs affecting plant height components.Of these,qtl₇ had effects simultaneously on lengths of panicle,and first,second and third internodes;qtl₁ and qtl₂ simultaneously on lengths of forth and fifth internodes.A total of 19 pairs of significant epistatic QTLs were detected.Among these,there were 2 or more pairs of epistatic QTLs for each plant height component,and it was found that one pair of epistatic QTLs simultaneously controlled several different traits and one QTL interacted with other different QTLs to affect diffe- rent traits.These results have revealed the genetic basis of plant height components in rice which correlated more or less with each other,and are of benefit to fine genetic manipulation of plant height in rice breeding.