Otoliths of the gag grouper, Mycteroperca microlepis, sampled from the headboat fishery off the southeastern United States were examined to determine age. The oldest fish collected was age XIII and 1,201 mm total length. Back-calculated mean lengths of 136 fish ranged from 269 mm at end of year 1 to 1,080 mm at end of year 13. The von Bertalanffy equation describing theoretical growth in length is Lt= 1,290 (1 - e-0.12154(t+1.127)), where L = total length (mm) and t = years. The length-weight relationship is described by the equation W = 1.2 × 10-8L2.996, where W = weight in kg and L = total length in mm. Only slight differences were noted in length-weight relationships between geographical locations. The average fish landed by the recreational fishery was 825 mm total length and 6.56 kg. Approximately 34% of the gag landed were age × and older. Apparently the rate of natural mortality increases drastically after age XII.