The aim of this study is to determine the most reliable bony structure for ageing of Pleuronectes flesus luscus inhabiting the Black Sea. The age determination method and its accuracy are the most important subjects for the evaluation of age-weight-length relationships in fisheries biology, since the estimates of survival, growth and mortality rates, and the analysis of year classes and recruitment all depend on age structure. In this study, scales, vertebrae and otoliths removed from each fish were examined by two readers three times each without reference to any data except the date of capture. The precision of readers and structure were estimated and the ageing error was determined by analysis of variance. The results are shown in tables.