Tannin-containing and tannin-free members of two pairs of near-isogenic lines of Vicia faba were studied in glasshouse experiments at Plant Breeding International Cambridge in 1989 to determine the cause of poor establishment of tannin-free lines in the field. Tests in field soils demonstrated marked differences in disease severity and growth, the tannin-containing lines being the more resistant to Fusarium culmorum and F. solani, the principal pathogens isolated. Susceptibility was not attributable to testa damage in tannin-free lines. In further tests on a range of varieties, some tanninfree and low-tannin, coloured-flowered varieties were as resistant as standard high-tannin lines. The results indicate that it should be possible to select for resistance to seedling infection and to subseque1t poor establishment among tannin-free lines and varieties.