Cohorts of 3-6 patients receive escalating doses of 17-AAG until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 of 6 patients experience dose-limiting toxicity. Once the MTD is determined, up to 6 additional patients with leukemia receive 17-AAG at the MTD as above. If these 6 patients tolerate this regimen, another 6 leukemia patients receive 17-AAG IV over 60 minutes on days 1, 4, 8, 11, 15, and 18.