A more convenient synthetic route to 2-bromo-2'-deoxyadenosine (5) is reported, and results indicating significant antitumor activity of 5 against three murine tumors (L1210 leukemia, B16 melanoma, and M5076 ovarian carcinoma) are presented. The antitumor activity is very schedule dependent, being much greater when the drug is given q 3 h (×8) every 3rd or 4th day than when given by single daily administration. Toxicity of 5 for the tumor-bearing host is also very schedule dependent. Thus, on the q 3 h schedule of administration, a greater cumulative dose is tolerated by the host, and the therapeutic effectiveness of 5 is enhanced accordingly. © 1984, American Chemical Society. All rights reserved.