the use of spontaneous species as green manure in the production of vegetables is slowly starting to produce satisfactory results. the purpose of the present study was to evaluate the productive performance of lettuce at different quantities and times of decomposition of dry scarlet starglory (merremia aegyptia l.) incorporated into the soil. the present study was carried out from october to december 2006 in a vegetable garden of plant sciences department of the universidade federal rural do semi-árido (ufersa), mossoró-rn？ brazil. the experimental design was a randomized complete block with the treatments arranged in a factorial 4 x 4 + 1, with three replications. the treatments consisted of the combination of four dry scarlet starglory amounts incorporated into the soil (2.6; 5.2; 7.8 and 10.4 t ha-1 of dry matter) with four different decomposition times (0; 10; 20 and 30 days before transplanting of lettuce - dbt), plus one additional treatment (80 t ha-1 of cattle manure, a traditional treatment in the lettuce cropping). the lettuce cultivar grown was 'babá de ver？o'. the evaluated characteristics were: height and diameter of plants, number of leaves per plant, fresh and dry mass of the lettuce shoots. the incorporation of dry scarlet starglory into the soil influenced the productive performance of lettuce in a positive way, thereby showing promise for use as a green manure. the highest fresh mass amount of the lettuce (15.33 t ha-1) was obtained with the incorporation of 6.68 t ha-1 of dry scarlet starglory to the ground in time of 30 days before transplanting of the lettuce.