A separation/enrichment procedure has been developed for the determination of selenium in garlic and onion samples by electrothermal atomic absorption spectrometry (ET-AAS) as a slurry sampling after preconcentration with 3,3-diaminobenzidine (DAB) reagent on the activated carbon. The influences of pH, time, amount of carbon and complexing reagent were outlined. The effect of acids used in the digestion of samples was also studied and compared. Selenium level was found to be 0.024 mu g g(-1) for onion (n = 5; LOD - 0.5 mu g L-1; LOQ - 1.7 mu g L-1) and 0.015 Vg g(-1) for garlic (n = 5; LOD - 1.3 mu g L-1; LOQ - 3.3 mu g L-1). Three different samples of garlic were analyzed by ko-instrumental neutron activation analysis (k(0)-INAA) at the Jozef Stefan Institute (JSI). The data obtained by k(0)-INAA show that the content of selenium overlapped the results obtained by ET-AAS. (c) 2005 Elsevier Ltd. All rights reserved.