Twelve new polyphosphates were synthesized by reacting the monomers

i.e. N

N'-di(ω-hydroxyalkyl)-5-fluorouracil-1

3-diacetamide

N

N'-di(ω-hydroxyakyl)uracil-1

3-diacetamide

N

N'-di(ω-hydroxyalkyl) thymme-1

3-diacetamide

with bis-(2-chloroethyl) phosphoramidic di-chloride or ethyl dichlorophosphate. The antitumor activity of some of these polymers were tested against EAC

HSC and S18v in mine. The polyphosphates containing both 5-fluorouracil and nitrogen mustard exhibit higher antitumor activity. The inhibition ratio of polymer (IVb)against Ehrlish ascites reaches 60% The relationship between the component of the polymers and the antitumor activity were also discussed.