Age, growth, and sex ratio were determined from 484 yellow-phase American eels (Anguilla rostrata) collected from brackish waters (16.4 g/liter; mean salinity) in Charleston Harbor, South Carolina. Eels averaged 4.4 years, 437.6 mm total length, and 189.9 g live wet weight. Length-weight relationship was: log W = -5.7156 + 3.0067 log L. Length and weight increases were greatest in the third and fifth year of age, respectively. The population consisted of 85.5% mature females, 7.9% advanced females, and 6.6% males. Mature and advanced females averaged 1.6 and 3.1 years older than males (2.7 years), respectively. Males were consistently smaller than females for each age class.