The evaluation of abalone (Haliotis spp.) restocking programs might be improved by the use of microchips attached to seeds [ca. 20–30mmshell length (SL)]. Preliminary studies were conducted to standardize thismethodology and to assess tag retention and the potential impacts of tagging red abalone (Haliotis rufescens) seeds (initial averages: 26 mm SL, 2.5 g total weight) with passive integrated transponder (PIT) tags (9×2mm, Biomark, HPR Plus Reader). Tags were placed in previously made grooves in the shells and glued with a cyanoacrylate adhesive fast cured with sodium bicarbonate. Laboratory trials showed that metabolic rate increased in tagged seeds compared with untagged controls (t = 4.74, P = 0.009) immediately after the tagging procedure, but this effect was not significant after 3 h (t= 1.43, P = 0.23). Food (Macrocystis pyrifera) consumption after 24 h was similar by seeds marked with PIT tags, plastic tags, both tags, and untagged controls (F= 0.12, P = 0.94). Tag retention and survival was 100% after 108 days in all treatments and no effects were detected on growth rates in length (range=0.92–1.11 mm/mo, F= 0.72,P= 0.57) or weight (range= 0.30–0.44 g/mo, F=2.44,P= 0.16). Results from a small-scale field experiment in tide pools, suggest that the detection of planted abalone seeds can be significantly improved when these are marked with PIT tags, compared with those marked with conventional plastic tags. Improvements should, however, bemade regarding antenna design and reading distance to optimize the use of this technology to evaluate restocking programs.