This study was done at Sakha Experimental Station, ARC, Egypt, during three seasons (2020-2022). Triple test cross manner was employed to disclose epistasis, additive, and dominance components of genetic variability for cotton yield, its components and fiber quality traits, three testers: Giza 96(L₁), S.101(L₂) and their F₁ hybrid(L₃) were crossed as male parents to seven cotton lines as female parents. Differences were significant concerning genotypes, hybrids, parents and lines for all traits and among testers for yield traits. Total epistasis was present for all the studied traits except for micronaire reading. The (i) type of epistasis (additive x additive) was significant for yield and its component traits and fiber quality traits except for micronaire reading. While the (j+l) type (additive x dominance and dominance x dominance) was significant for seed cotton and lint yield/plant, lint% and lint uniformity index. The (i) type was higher than the (j+l) type for all the studied traits except micronaire reading. Both additive and dominance were important for controlling the studied traits except boll weight, micronaire reading and Pressely index, only additive genetic effect was important. Additive component was extremely higher than dominance component for all traits. Degree of dominance was less than unity for all studied traits, indicating partial dominance. Most of the lines did not share significant positive portion to the total epistasis for most traits. The results illustrated that the role of epistasis must be in breeder's consideration during planning a breeding program for improving economic traits in cotton.