Radical oxygen species (ROS) are produced and released during hypoxia, especially in mitochondria. Several variables which commonly used to monitor ROS activity in cell are malondialdehyde (MDA), reduced glutathione (GSH) and catalase. In this study, these variables had been measured and studied to evaluate the effects of chronic hypoxia on rat kidneys. Hypoxic condition was created using a hypoxic chamber gassed with a mixture of 8% oxygen and 92% nitrogen. Rats were placed in this condition for 3 and 14 days. A control group is placed in environmental atmosphere. Kidney protein concentrations were measured by Warburg-Christian method. Wills’ method was used for measuring MDA and Ellman’s method for GSH. Catalase activities were measured by measuring hydrogen peroxide (H2O2) decomposition directly by observing the decrease of the extinction at 210 nm. Catalase activities were significantly higher in day 3 and 14, even though day 14 activities were lower than day 3. On the other hand, protein, MDA and GSH concentration showed no significant differences between those groups. From this study, it was concluded that chronic hypoxia might cause different conditions of MDA, GSH and catalase activities in kidney. Keywords: Hypoxia, malondialdehyde, reduced glutathione, catalase activities, kidney