Age and growth of lemon sole (Microstomus kitt) were determined from 115 specimens collected in the Celtic Sea and in the North Sea in 2006 and 2007. Total length is ranged from 11 to 44 cm, while total weight varied between 12 and 1040 g. Age estimation was based on otoliths readings. The oldest male and female were estimated to be 9 years old. The length–weight relationships parameters for lemon sole in the Celtic Sea and in the North Sea were W=0.0043*TL3.2860 and W=0.0062*TL3.1505 respectively. Weight including both sexes increased with positive allometric growth. The von Bertalanffy growth equation in the North Sea was fitted on the basis of mean length-at-age data resulting in parameters values of TL∞ = 36.44 cm (S.E. = 0.484), K = 0.187 /y (S.E. = 0.069), t0 = -1.371 (S.E. = 0.701). Females appeared to grow more rapidely than males.