Abstract: We investigated phenotypic distributions of spikelet number per panicle (SNP), filled grain number per panicle (FGP), panicle length (PL), primary branch number per panicle (PBNP) and secondary branch number per panicle (SBNP) in P₁, P₂, F₁, B₁, B₂ and F₂ generations of 2 crosses of Bingbao 3201×Bingbao 3145 and Bingbao 3214× Bingbao 3205 of Oryza sativa spp. japonica. We also conducted genetic analysis of the 5 traits by using the mixed major gene plus polygene inheritance models. Bingbao 3201 and Bingbao 3205 had extremely small panicles, whereas Bingbao 3145 and Bingbao 3214 had extremely large panicles. All 4 lines were selected from a recombinant inbred line population bred previously in japonica rice. Three segregation generations of both crosses revealed transgressive segregation of FGP, PL, PBNP and SBNP but not SNP. Genetic analyses showed that PBNP was controlled by 1 major gene plus polygenes. Traits of SNP, FGP, PL and SBNP were controlled by 2 major genes plus polygenes. Traits of SNP, FGP, PL and SBNP were mainly governed by major genes, while PBNP was mainly governed by polygenes.