The intensification of agriculture and uncontrolled application of agrochemicals has resulted in an in creased loading of ground water with pesticides, greatly im pacting ecosystems by changing the biodiversity and threatening aquatic organisms. The aim of this study is to inve stigate the underlying effects of the mixture Fludi oxonil – Difenoconazole, a newly introduced fungicide for th e treatment of seeds, on an alternative cellular mo del: The ciliated protist Paramecium sp. Exposure experiment s were conducted at 28°C and various endpoints were studied. We first interested to investigate the effects of s ublethal exposure to Fludioxonil – Difenoconazole o n population growth. Paramecium cells were exposed to four conce ntrations of (0.1, 0.5, 1, 1.5 mg/l) and the growth kinetics was followed for 96 hours. We also measured the oxygen consumption via a polarographic study. Under the sa me condition, total proteins rate, Glutathione content (GSH) and enzymatic activity of Catalase (CAT) wer e investigated to evaluate antioxidative response to fungicide effects. After 96h of treatment, the resu lts showed a significant decrease in growth rate of about 70% in cells treated with 1.5 mg/l. Paramecia exposed to different concentrations of Fludioxonil - Difenoconazole show ed a strong disruption in respiratory metabolism. O n another hand, the monitoring of biomarkers has demonstrated a significant decrease in total proteins rate at t he highest concentration. The present finding revealed a disru ption of enzymatic activity of Catalase and a deple tion of GSH content in dose dependent manner. By the obtained r esults, we may suggest the occurrence of oxidative stress generated by the studied xenobiotic on the ciliated protozoan Paramecium sp.