We measured susceptibilities of Ugandan Plasmodium falciparum isolates assayed on the day of collection or after storage at 4°C. Samples were incubated with serial dilutions of 8 antimalarials, and susceptibilities were determined from 72-h growth inhibition assays. Storage was associated with decreased growth and lower 50% inhibitory concentration values, but differences between assays beginning on day 0 or after 1 or 2 days of storage were modest, indicating that short-term storage before drug susceptibility determination is feasible.