During a two-year period (1996-1997) we conducted studies on the effects of crop density on root yield and quality of sugar beet cultivars, susceptible and tolerant to rhizomania, grown on the soil infested and uninfested by this pathogen. The results obtained are of importance for both agricultural science and practice. The highest difference in sugar beet studied characteristics was achieved between infested and uninfested soil, between tolerant and susceptible cultivars, and the lowest between crop densities. On the soil infested by rhizomania, on average, root yield was lower by 22.84 t/ha, sugar content by 2.49%, crystal sugar yield by 4.64 t/ha per cultivar and crop density. Tolerant cultivar KWS rama produced higher root and sugar yields on both infested and uninfested soil. However, susceptible cultivars Al omona and Delta, grown on uninfested soil, had higher sugar content in sugar beet root by 0.53%. Increased crop density resulted in higher root and sugar yields, however, considerably higher in the tolerant cultivar and on soil infested by rhizomania.