Two hundred and six mapped microsatellites markers evenly distributed on the 26 chromosomes of Gossypium hirsutum L. were used to monitor the introgression of DNA fragments coming from the Australian species G. sturtianum Willis and the wild American diploid species G. ramondii Ulb. in a population of BC1, BC2, BC2S1, BC2S2, BC2S3, BC2S4, BC2S5, BC2S2/BC1, BC2S2/BC1/S1,BC3, BC3S1, BC3S2 and BC3S3 derivatives obtained from the G. hirsutum x G. raimondii x G. sturtianum (HRS) trispecific hybrid. In the most advanced backcrossed progenies of the HRS hybrid, the only plants that are still showing a drastic inhibition of gossypol synthesis in a part of their seeds and a normal glanding pattern in their other organs contain fragments of G. sturtianum DNA related to c02- c1, c03-c17 and c06-c025 linkage groups of G. hirsutum. In these plants, all the SSR markers associated to the G. sturtianum c06-c025 DNA fragment introgressed in G. hirsutum remain heterozygous after numerous generations of selfing. One can thus suppose that this alien chromosomic fragment may also carry a recessive lethal factor, which expresses itself when it becomes homozygous. If this hypothesis proves to be true, it will be necessary to break the linkage that exist between this lethal factor and the gene(s) responsible for the expression of the trait of interest in order to develop stable homozygous cotton lines with very low gossypol content in the seed and high gossypol content in the aerial parts.