AbstractAmong the common agricultural crops winter‐rapeseed (Brassica napus L.) is considered to be especially susceptible to varying environmental conditions. The commonly used stability statistics, which measure these fluctuations, are based on the yields of genotypes in different environments. An improvement of stability analysis may be obtained by an additional estimation of stability using yield components rather than absolute yield values. Relationships between stability of seed yield (SY) and stabilities of plant densities (PD) and of single plant yield (SPY) were examined for four winter‐rapeseed varieties, their six F1's and their six F2's. Environmental variance was applied to estimate phenotypic stabilities. Furthermore, generations were compared for their stability in SY, PD and SPY. Regarding all genotypes and generations the correlation coefficients did not show any relation between stability of SY and stabilities of PD and of SPY (r = ‐0.04 and r = ‐0.17). Comparing generations the F2 showed a higher stability of SY than varieties and F1, But no consistent results were obtained regarding PD and SPY. The pattern of the heterotic effects of stability of yield components PD and SPY were different from the respective pattern of SY. Eg although possessing desired heterotic effects in stability of PD and SPY some crosses showed undesired heterotic effects in stability of SY. Therefore, a theory of multiplicative heterosis of stability should be developed in analogy to the corresponding theory for yield.