Excessive growth of the cotton plants Gossypium hirsutum L. in some regions causes laying and deficient luminosity, and a consequent lowering in yield and type of cotton. Such problems are specially serious in the case of mechanical picking where between-row spacing is fixed at about 40 inches. Combined effects of the use of growth limitant chemical CCC (Chlorocholine Chloride) and population density were studied in 1972/73 and 1975/76 in four localities of the State of São Paulo. Near Campinas and Sumaré, the effects of 4, 8 and 16 plants/meter (respectively 40,000, 80,000 and 160,000 plants/ha) with and without CCC were studied. At Tietê and Piracicaba, 4, 8, 16 and 32 plants/meter were used (respectively 40,000, 80,000, 160,000 and 320,000 plants/ha). Only the treatments of 16 and 32 plants/meter were combined with CCC application. The concentration of CCC used was of 50 g a.i../ha applied from 50 to 70 days after emergence of the plants. The results showed that CCC limited the growth of plants, increased earliness of yield, decreased lint percentage and increased fiber length, boll and seed weight. There was no effect observed on cotton yield, fiber length uniformity, Micronaire, Pressely and fiber maturity. Higher density resulted in higher yield. High density also caused better length of fiber and lower boll weight.