A study examined the pattern of stability of ergometrine, methylergometrine, and oxytocin, all used to treat and prevent excessive bleeding after vaginal delivery. It included observations of how longterm dark storage at both 25 and 30 degrees Celsius, short-term exposure to higher temperatures, and short-term exposure to light affect these drugs. Field surveys in Gambia, Malawi, Sudan, and Zimbabwe involved taking ergometrine injection samples from rural health facilities and medical reserves. The active ingredient in just 29% of the field samples met US and British Pharmacopoeia (USP/BP) limits of 90-100% of the stated content. 28% had less than 60% of the active ingredient. Field data on methylergometrine were available. The limited field data on oxytocin indicated that the quality was fine, since many samples had more active ingredient than stated. Overall, no differences in stability existed between ergometrine and methylergometrine. Sizable differences did exist between brands, however. Thus, programs should procure methylergometrine and ergometrine from a reliable supplier whose submitted documents comply with World Health Organization certification. The active ingredient in ergometrine and methylergometrine under refrigeration for 12 months fell an average of to 4 to 5%. At 30 degrees Celsius in the dark for 12 months, it fell on average 25%. At 40 degrees Celsius in the dark for 2 months, it fell about 5%. At 21-25 degrees Celsius in the light, the active ingredients fell 21-27% after 1 month and more than 90% after 12 months. On the other hand, refrigerated storage for 12 months did not reduce the potency of oxytocin. At 30 degrees Celsius in the dark for 12 months, the active ingredients of oxytocin samples fell on average 14%. Light did not destabilize oxytocin. Any noticeable difference between the color of (methyl)ergometrine and clear water means that the level of active ingredient is less than USP/BP standards (sensitivity 100%, specificity 85%). Thus, health workers should view every injection to ensure that it looks like clear water.