The stability was determined for injectable 2% morphine (I) solutions stored in ampuls and ampins (automatic ampul injection) for 1 yr. at 20° and 40°.Addition of 0.005-0.01% ethylenediaminetetraacetic acid (EDTA) largely prevented discoloration and formation of oxydimorphine (Thörn and Agren, C.A. 43, 3973e) in the solutionTo stabilize I solutions, it is recommended to add EDTA, then adjust pH to 3-3.5.0.1% Na2S2O5 had no stabilizing effect.The addnl. pressure in the ampin did not appear to contribute to the decomposition of the I solution; however, by decreasing the O content and replacing with N, an increase in stability was noted.