Four L. virosa accessions have been used as sources of disease resistance. Resistance to Bremia lactucae and two viruses, BWYV and LMV, were identified. To transfer these resistances to lettuce, in vitro embryo rescue must be used to obtain the first BC with L. sativa. Two resistances to Bremia were studied in fertile lines of lettuce issued from interspecific crosses followed by several BCs and selfing. The resistance introgressed from each L. virosa was efficient against all tested isolates. The hypothesis of two dominant genes will be discussed in relation with segregation obtained in segregating populations (F2 and F3). The study of inheritance of virus resistance was conducted in a segregating population between L. virosa genotypes. The hypotheses of one dominant gene (Bw) for resistance against BWYV and one partly dominant gene (Mo3) for resistance to LMV were proposed. Many heterozygous plants for Mo3 were necrotic after LMV inoculation. The introgression into L. sativa of the virus resistance genes from L. virosa was very laborious due to physiological problems of plants growth especially with Mo3. After several BCs with different varieties and self-pollinations, the plants were still necrotic; many plants died at the vegetative stage due to very weak roots, especially the heterozygous one, or at the bolting due to stem necrosis. The BWYV resistant lines, several self-pollinations after only one BC, had small heads or had not yet headed. Nevertheless, after several BCs, some fertile resistant lettuce plants were obtained.