1. Administration of a riboflavin antagonist to nonleukemic Wistar rats resulted in granulocytosis without lymphopenia.
2. The analog did not have any beneficial effect on the course of myeloid chloroleukemia in Wistar rats. There was a tendency for the leukemic rats receiving the analog to have larger numbers of abnormal granulocytes than blank-injected controls, although the differences were not statistically significant.
3. Administration of TEPA resulted in rapid and prolonged remission of the myeloid chloroleukemia, as noted by others.