The present investigation involved testing the effect of different carbon sources (glucose, sucrose and starch) as well as different nitrogen sources (peptone, yeast extract and urea) on the production of vitamin B 12 using Klebsiella pneumonia grown on mixture of agriculture wastes (wheat straw and rice bran). The results show that glucose was the best carbon source compared to the other di-and polysaccharides used. The best vitamin B 12 output (63.87 µg/L) was obtained at 3 g/L glucose. On the other hand, peptone appeared to be the most suitable nitrogen, since it gave (57.8 µg/L) of B 12 compared to the other nitrogen sources used. Statistical analysis for the obtained results had been carried out and the data showed that glucose and peptone additions were highly significant compared to the other sources under investigation.