This study compares Staphylococcus aureus ATCC 29213 and Pseudomonas aeruginosa ATCC 27853 biofilm and planktonic cell susceptibility to the selenium and tellurium oxyanions selenite (SeO3(2-)), tellurate (TeO4(2-)), and tellurite (TeO3(2-)). P. aeruginosa planktonic and biofilm cultures reduced the selenium and tellurium oxyanions to orange and black end-products (respectively) and were equally tolerant to killing by these metalloid compounds. S. aureus planktonic cell cultures processed these metalloid oxyanions in a similar way, but the corresponding biofilm cultures did not. S. aureus biofilms were approximately two and five times more susceptible to killing by tellurate and tellurite (respectively) than the corresponding planktonic cultures. Our data indicate that the means of reducing metalloid oxyanions may differ between the physiology displayed in biofilm and planktonic cultures of the same bacterial strain.