Within the EU project SARDYN, tagging laboratory experiments and operations at sea were designed to study the movements of sardine (Sardina pilchardus) off the Iberian peninsula. In the summer of 2003, around 2500 fish were caught and transferred alive to aquaculture tanks (IEO - Vigo and IPIMAR - Olhão). Mortality ranged between 10-30% in the first week, mainly due to stress and scale loss associated to fishing and handling. Feeding (dry pellets) and schooling was soon assumed in the tanks and subsequent mortality has been close to zero for almost a year. Three tags (T-bar in the dorsal fin, Streamer in the operculum and the tail and Fingerling in the tail) were tested in several trials. All tags produced low mortality (< 5%), and the final choice for tagging at sea (Streamer in the tail) was based on the rate of detachment, tag visibility, interference with swimming and feeding behaviour and easiness of operation. In the summer of 2004, up to 30000 sardine are aimed to be tagged off the Iberian Peninsula (southern and northwestern Portugal, western Galicia and central Cantabria). A publicity strategy has been devised, aiming to enhance the probability of tag recoveries.