Tumor Induction in Monkeys after Administration of Dimethylhydrazine

1,2‐Dimethylhydrazine (DMH) was administered subcutaneously to nine Macaca fascicularis monkeys (6 males and 3 females) at doses of 16 mg/kg body weight, three times a month for two years. Colon cancer was detected in two male monkeys after total DMH doses of 1080 and 3696 mg (528 and 400 mg/kg body wt., respectively). A uterine tumor was induced in one female monkey which received 3648 mg of DMH (608 mg/kg body wt.). Latent periods of tumor development were 34, 47 and 55 weeks, respectively. Histologically, the colon tumors had the structure of adenocarcinoma in both cases and the uterine tumor was diagnosed as flbromyoma.