It is well-known that organotellurium compounds can have antioxidant activity in vitro, but in vivo these compounds can be potentially  toxic to rodents. The diethyl 2- phenyl- 2 tellurophenyl vinylphosphonate is a new organotellurium compound that have never been tested in vivo for toxicological evaluations. The objetive of this study was to observe a possible toxic propertie of this organotellurium compound through delta-aminolevulinate dehydratase (δ- ALA-D) activity, body and organ weight and survival index after a subchronic treatment with diethyl 2- phenyl- 2 tellurophenyl vinylphosphonate or with diphenyl ditelluride, which was used  as a comparative parameter of letality. Fourty Albino male mice were divided into 8 groups and were daily treated subcutaneously for 12 days with DMSO (2.5 mL/Kg), saline 0.9%, 25, 75 and 250 mmol/Kg of diethyl 2- phenyl- 2 tellurophenyl vinylphosphonate or 12.5, 25 and 75 mmol/Kg of diphenyl ditelluride. The body weight gain was monitored each 4 days and the survival observed every day. After the end of the treatment , the animals were killed and liver, kidney and brain were removed, weighted, homogenized in buffer, and centrifuged to obtain S1 to δ- ALA-D activity assay. Body weight of mice treated with diethyl 2- phenyl- 2 tellurophenyl vinylphosphonate was not altered untill the end of the 12 days as well as the organs weight. Diethyl 2- phenyl- 2 tellurophenyl vinylphosphonate did not inhibited δ- ALA-D activity at all administed doses in all tested tissues. One interesting finding was the very low mortality of animals treated with Diethyl 2- phenyl- 2 tellurophenyl vinylphosphonate when compared to animals injected with diphenyl ditelluride. All animals treated with diphenyl ditelluride died within four days of treatment, whereas only one animal treated with 250 μmol/kg of diethyl 2-phenyl-2-tellurophenyl vinylphosphonate has died. This dose is at least 20 times higher than the lowest dose of diphenyl ditelluride administered. These data indicate an advantage of diethyl 2-phenyl-2-tellurophenyl vinylphosphonate over diphenyl ditelluride that causes high mortality level even when tested at lower doses.