The age and growth parameters of Brazilian flathead, Percophis brasiliensis, from the southwest Atlantic coastal waters (34°-41°S) were determined for samples collected in spring (n = 853; years 1998 and 2000) and winter (n = 596; year 2004), whereas age was validated through the edge analysis of otoliths collected in 2007 (n = 1367 otoliths). The indices of precision APE, V, and D were used to test the reproducibility, between agers, of the ages determined from 845 otoliths. Maximum determined ages were 19 years for males and 15 years for females. One opaque and one translucent band are laid down per year, in the sagittal otolith. According to the APE (0.668%), V (1.121%), and D (0.647%) indices, the age determination was consistent. Von Bertalanffy's growth parameters [males: spring (L∞ = 58.1 cm, k = 0.26 year-1, t0= -2.02 years), winter (L∞ = 58.7 cm, k = 0.21 year-1, t0 = -2.90 years); females: spring (L∞ = 65.2 cm, k = 0.29 year-1, t0 = -1.15 years), winter (L∞= 63.5 cm, k = 0.26 year-1, t0 = -2.01 years)] were significantly different between sexes and seasons. From the first year of life, females grow faster and reach greater lengths than males of the same age due, probably, to an asynchronism in the sexual maturity.