I. To evaluate for disease response to 8-chloro-adenosine in refractory/relapsed acute myeloid leukemia (AML) on each dose level tested. (Phase I) II. To obtain estimates of remission duration and survival probabilities (overall and event-free). (Phase II) III. To obtain an estimate of the overall response rate (CR + CRi + partial response [PR]). (Phase II) IV. To summarize and evaluate toxicities by type, frequency, severity, attribution, time course and duration. (Phase II)