The main aim of this paper is the use of Diphenylamine Sulfonate (DPAS) redox indicator in its oxidized or reduced form in microdetermination of non-steroidal anti-inflammatory drugs such as Ketoprofen (KETO) and Indomethacin (INDO) in pure and in their pharmaceutical preparations. DPAS prepared in its oxidized form by its titration against K2Cr2O7 in 2 N sulfuric acid to give its blue-violet colour of quinoid form of λmax = 555 nm. The reaction between DPAS oxidized blue-violet form and each drug within 10 min has been studied in the visible range. This study proved the formation of red products. The reactions of the indicator reduced reread form and the studied drugs are also studied in the UV range at 255 nm after passage of 30 min leading to the form of brown products. Also the stoichiometries of these reactions are formed to be 1:1 and 2:1 (Drug: indicator) and the proposed equations representing them are also formulated. The two proposed reactions in both Vis and UV ranges are applied for microdetermination of these anti-inflammatory drugs in both standard and in their pharmaceutical formulations. The analytical parameters of the reactions of DPAS in its two forms and the given drugs in both Vis and UV ranges such as standard deviation (SD), relative standard deviation (RSD), Sandell's sensitivity (S), LOQ and LOD of were calculated in order to check accuracy, sensitivity and precision of the given procedures. In the visible region; Beer's law has been valied in the concentration range of KETO = 5.1-50.9 μg mL-1 and INDO = 10.7-71.6 μg mL-1. Beer's law in the UV range procedure valied in the concentration ranges of KETO = 1.27-6.36 μg mL-1 and INDO = 0.72-14.31 μg mL-1 The values of % recovery are found to be 100.39 and 100.24 and those of SD are 0.2 and 0.14 in violet form; while % recovery = 99.95 and 100.25 and those of SD are 0.031 and 0.015 in brown form for KETO and INDO respectively. These values refer to the accuracy, reliability, and precision of the proposed procedures. The proposed methods had been applied successfully for the analysis of the studied drugs in pure forms and pharmaceutical formulations. As example KETO had been analyzed in Ketolgin tablet (UV- region) in the concentration range of 1.53-4.07 μg mL-1 of recovery percent = 99.36-100.61, SD = 0.01-0.03. The results obtained were found to be in good agreement with those obtained by official methods. This evaluation had been done by F- and t- tests.