Ruminal bolus for electronic identification of Sarda goats under extensive farm conditions and the retention rate and health effects of ceramic boluses (70 mm x 21 mm, 75 g) enclosing passive transponders half-duplex (32.5 mm x 3.8 mm) were evaluated. A metallic balling gun was used in order to insert 1411 boluses into goats (1132 adults and 279 kids) and the effect on health and retention rate were determined over 8 months. The location of boluses in reticulum after the administration was checked with a hand-held reader. To verify the readability and the retention rate of bolus used as control readings at 1, 7, 30 and 210 days were recorded under dynamic conditions in a race-way, using a fixed reader with a frame antenna (94 cm x 52 cm). Health status was not affected by boluses in the control and the retention rate of boluses after the 8 months was 99.6% with six boluses lost. The ruminal boluses, when retained, showed a 100% readability in static conditions (restrained animals) with the hand-held reader. Farmers expressed satisfaction and interest in the electronic identification system. The use of the ceramic bolus is recommended as a safe and tamper-proof method for electronic identification of goats. This can improve the reliability for identification and management of goats within the extensive conditions in the Sardinia island.