In Cerete, cotton-producing region of the Colombian Atlantic Coast, ethrel (0.0; 1.5; 2.0; 3.0; and 4.0 It/ha) was appilied to Gossypium hirsutum L. var. Deltapine 61 during different staages offruit development (70%, 80%, 90% of half-ripe fruits -HRF-; and 10 days befo re the first harvest). Ethrel induced synchronic ripening of fruits, increased fiberseed production and achieved an opportune and total cropdefoliation, facilitatingcollection procedures of fiber-seed. In plants with 70% HRF and treated with 3.0 It/ha of ethrel, the precocity index was near 90%, fiber-seed production at first harvest was 2.85 Ton/ha and total production was 3.38 Ton.ha an increase, over the control, of 830 Kg/ha.