Stability of injectable amphotericin B from menstruum was studied after Placing under the following conditions: high temperature, high humidity, and light for 10 days, RH 60% at 25°C for 6 mo, and at 2°C-8°C for 36 mo. Exptl. parameters include the appearance, the degradation product amphotericin A, loss on drying, microbial assays, composition and relative substances. Results indicated that amphotericin B for injection is unstable to light and high temperature, while stable in ordinary storage condition.