Oats or Avena comprises about 30 species; one of the examples A.sativa and A.abyssinica.InrnEthiopia A.abyssinica is made into 'injera' and other products. Underutilized crops are thosernwhich are neither cultivated in an organized forming system nor processed by establishedrncommercial processing. In this research, effect of natural fermentation with time on proximaterncomposition physicochemical, phytochemical, anti-nutritional, functional and acute toxicity ofrnA.abyssinica flour was studied. A. abyssinica sample was collected from north Show zone,rnAngolela and Tera woreda Chacha area. A total of 15kg sample was collected from a localrnmarket, cleaned, dehulled, and finally packed in polyethelene bags. All the analysis wasrnperformed triplicate. results were expressed as mean Â± standard error (SE). In the proximaternanalysis; crude protein, carbohydrate, moisture, crude fat, and Fiber content ranged from 11.46rnto 12.83, 72.68, 8.33 to 11.38, 7.00 to 8.00% and 7.18 to 9.92% respectively. From the currentrnstudy, Phytochemical properties such as total phenolic and flavonoid contents was ranged fromrn374.7 to 652.8 mg GAE/g and 161.42 to 184 mgDE/g respectively. Physicochemical propertyrnrevealed that, hundred seed weight of A. abyssinica seeed was 3.11g also PH ranged from 0.02rnto 0.2 respectively. In the determination of functional properties six parameters were studiedrnand the result ranged from 130.36 to 209.33 for water absorption capacity, 2.00 to 2.34 for oilrnabsorption capacity, 37.66 to 45.56 for emulsion property, 0.62 to 0.30 for bulk density, 55.73 torn60.36 for dispersibility and 0.47 to 0.63 for foaming capacity. Anti- nutritional factors likernphytate, tannin, oxalate and alkaloids were determined, for raw samples 2.09, 2.36, 0.002 andrn0.61 also for fermented samples ranged from 0.71 to1.94, 0.86 to 1.31, 0.004 and oxalate andrnalkaloid respectively. In the analysis of acute toxicity no toxic effects were observed.