AbstractTo study the genetic structure of open‐pollinated faba bean varieties, three sets of genotypes were generated from each of the varieties ‘Minica’, ‘Kristall’, and ‘Deiniol’: (1) inbred lines developed by single‐seed descent in bee‐proof isolation cages, (2) intravanetal and (3) intervarietal F1‐hybrids produced by controlled hand crossing. In 1989 and 1990, a total of 144 entries, including the three open‐pollinated source varieties, were grown in single‐row plots with two replications at two locations in Western Germany.Performance data of the inbred lines revealed relatively large genotypic variability within each variety, for all the characters studied, which was greater in ‘Deiniol’ and ‘Kristall’ than in ‘Minica’. An average yield heterosis of 20 %, 39 % and 57 %, respectively, was found for the intravarietal hybrids, whereas that of the intervarietal hybrids varied between 70 and 73 %. Compared to the mean yield of the inbred lines the superiority of the open‐pollinated source variety was small and not significant in ‘Minica’ (6 %), but it was large and highly significant in ‘Kristall’ (22 %) and ‘Deiniol’ (37 %).The present investigation revealed in faba bean that similar performance levels of open‐pollinated varieties may result from either highper seperformance under inbreeding with low heterosis values or from lo