In this research, the biochemical and genotoxic impacts of three antibiotics, Ciprofloxacin, Levofloxacin and Amoxicillin were examined on a freshwater microalga, Neochloris conjuncta. Six concentrations (0, 5, 10, 15, 25, 50 and100 µg ml⁻¹) were used, and the pure algal cultures were exposed for nine days under laboratory conditions. MDA, SOD, CAT, ROS%, and Vitamin C were measured as reflective markers of oxidative stress responses; whereas the Comet Assay was conducted to detect DNA damage. The antibiotics resulted in different oxidative stress patterns, as shown regarding the results. Among drugs, amoxicillin produced the most intense biochemical disturbance, including high levels of CAT and SOD activities, which suggest considerable alterations in redox homeostasis. Moderate oxidative stress was provoked by Ciprofloxacin while Levofloxacin showed the less severe metabolic alterations. The genotoxicity study, however, revealed that DNA fragmentation was the highest in the case of Levofloxacin at its maximum concentration and subsequently Ciprofloxacin while Amoxicillin induced the lowest potent damages. Taken together, the results suggested that the antibiotics had different toxic effects on Neochloris conjuncta; among them Amoxicillin imposed the most oxidative stress, and Levofloxacin caused the most severe DNA injury. These findings also demonstrate the significance of including both biochemical and genetic endpoints into risk assessments concerning pollution since biochemistry was less sensitive than genotoxicity.