The Planning Group on Commercial Catch, Discards and Biological Sampling (PGCCDBS) identified the Red mullet (Mullus barbatus) and the Striped mullet (Mul-lus surmuletus) as species requiring an ageing workshop to evaluate and improve the age interpretation based on otolith reading. The Workshop is built on the results of the otolith exchange organized in 2008 and is the first ageing workshop for Red mul-let and Striped mullet. The overall result of the workshop exercises is that there are significant differences in age estimates among readers for the red mullet of the Mediterranean Sea and the striped mullet of the Eastern Channel. The image analysis exercise clarified that the lack of agreement can be due to the interpretation of the first ring for the red mullet of the Mediterranean Sea and the identification of the following rings for both spe-cies. Exploring the application of image analysis, the group agreed that applying such tools in the routine age estimation of the mullets may be very valuable. It gives the opportunity to use metrics to rule out doubt when defining the age structures to count and also gives a very useful exchange tool for the individual readers both within and between laboratories. The workshop after discussions and analyses identified some problems for the esti-mated age of the mullets. The group reached agreement on the definition of ageing guidelines mentioned in the present report and the aim is to employ these guidelines to eliminate some of the problems with e.g. false rings in the otolith structures. A col-lection of agreed aged mullet otoliths were started at the workshop. The reference collection will have to be expanded considerably through others exchange of otoliths and images.