tion. Yeast cells were grown in yeast extract-peptone-dextrose broth (1:2:2;%). 12 ml of DNA was used in each sample. Bleomycin: Samples with 12 ml of DNA were exposed to different Bleomycin doses (0, 0.015, 0.045, 0.15, 0.45, 0.5 UI/ml) for different times (24, 48, 72 hours). Electrophoresis: After treatments, DNA samples were electrophoresed in a 1% agarose gel (in 0.5 X Tris-Borate EDTA) at 80 V, 90min. The gel was stained with ethidium bromide 10mg/ml. Image analysis of gels: After electrophoresis, photography of the gel was taken and the images in jpg files were analyzed with the ImageJ 1.34s software. A DNA profile (intensity of signal versus migration distance) was obtained for each electrophoresis lane. The area under the curve, that is indicative of the content of DNA, was obtained automatically with this software in each profile. Results: Bleomycin induced DNA degradation that was increased with the increment of time of exposure and with the dose. The images of the gels analyzed showed that the DNA damage was about 20% of degradation at high bleomycin doses (0.45 UI/ml) and 24 hours of exposure. Longer exposure period (72 hours) induced a 30% of DNA degradation at a dose of 0.15 UI/ml, and a 50% of degradation at 0.45 UI/ml. Results showed a dose-response relationship that can be used to estimate the effective dose of bleomycin analyzing the DNA degradation obtained. Conclusion: Belomycin is a genotoxic agent that can induce DNA degradation time and dose dependent. The optimization of dose-response curves, like in this study, permits the estimation of the effective dose of exposure to a better evaluation of the antineoplastic activity based on the study of DNA degradation; which could be used for dosimetric purposes.