Abstract The uptake, toxicity, and elimination of atrazine and trifluoroacetate (TFA) were studied in early life stages of the zebrafish ( Danio rerio). Furthermore, the effects of these xenobiotics on soluble (s) and microsomal (m) glutathione S-transferases (GST) of zebrafish embryos were investigated using 1-chloro-2,4-dinitrobenzene (CDNB), 1,2-dichloro-4-nitrobenzene (DCNB), and [ 14C]atrazine. [ 14C]Atrazine was taken up by the embryos within seconds, unhindered by the chorions. It accumulated in the embryos by a factor of 19 after 24 h of exposure time. LC 50 (48 h) was determined at 36.8 mg/L. At a level of 5 mg/L atrazine, activities of s and m GSTs were elevated in most stages, especially in prim 6 and long pec stage (24, 48 h after fertilization, respectively). GST activity toward atrazine was detectable only in untreated D. rerio eggs, increasing with developmental time. [ 14C]Atrazine was eliminated from the embryos between 24 and 48 h, indicating a possible metabolism to a more hydrophilic GSH conjugate. [ 14C]TFA was taken up by embryos, reaching at maximum fivefold the concentration of the incubation medium after 10 h. The chorions served no physiological protection. TFA (1 g/L) caused low elevation of the GST activity. No acute toxic effects (48 h) were observed up to 4 g/L TFA.