Four groups of rainbow trout (Onchorhynchus mykiss) each with 60 females with an average body weight of 467 g were submitted to an aleatory assay in order to compare the efficiency of four diets containing different concentrations of carotenoid pigments, and to determine if pigment concentration and source had an influence on female gonad development and oocyte maturity. The first diet was the non-pigmented control (C). The second diet contained 100 mg kg(-1) of Carophyll Pink (CR). The third and fourth diets contained 200 (RC200) and 250 (RC250) mg kg(-1) of saponified red chili oleoresin, respectively. The results indicated significant differences (p < or = 0.05) between C and RC250, with respect to the gonado-somatic index (IGS), average gonad weight (PG) and average diameter of oocyte (DO), with CR250 showing higher IGS, PG and DO values. Treatments CR and CR200 presented similar values. At the end of the experimental period, only 10% of oocytes were mature in the RC250 diet.