Each year new chemicals enter the market and generate an increasing volume of residues, leading to health and environmental concerns. Although many of those compounds are known as toxic, a significant proportion do not have a proper hazard classification; they are potentially dangerous and able to generate harmful biological effects. Biochemical changes can be often translated as modifications in the morphology, behavior, or metabolic pathways, analyzed in a species known as bioindicator. Ethidium Bromide (EtBr) is a fluorescent stain used in protocols of Molecular Biology due to its intrinsic ability to intercalate between DNA nitrogenous bases. For this reason it is considered as mutagenic, although is not classified as carcinogenic by IARC (International Agency for Research on Cancer). The present work intends to analyze the phenotypic and biochemical effects on 15 generations of D. melanogaster exposed to different concentrations of EtBr. We used three different concentrations of EtBr and two control groups. For the positive control we used EMS (mutagenic) whereas the negative control was not exposed to any mutagen. The chemicals were fully mixed with the culture medium. Two generations were analyzed preliminarily, showing phenotypic abnormalities, involving the tergits, wings and pigmentation.   Another response to the exposition to EtBr and EMS was an increase in the number of fruit flies, a possible survival strategy. However, when we compared F1 and F2, the highest EtBr concentration displayed a 34% decrease in the productivity, remaining this parameter unchanged for the lower concentrations. Probably, this was caused by a cumulative effect, affecting flies' viability in that group.  This can also be verified by a delay in the life cycle, as well as by an increase in the number of individuals displaying morphological alterations.  No changes were observed for catalase and superoxide dismutase (SOD) electrophoretic patterns. For  6-esterase, we observed that the strain was heterozygous, so a new strain, homozygous for that enzyme, was selected for a new testing series. So far, after 4 generations, the same effects previously described have been observed, and the electrophoretic analysis will be carried out for esterase, catalase and SOD every three generations. Financial support: FAPESP (05/02418-6) and CNPq.