Abstract: High-resolution 1H (220 MHz) and I3C (68 MHz) nuclear magnetic resonance (NMR) spectroscopy was used to investigate the chemical stability of the anticancer drug cyclophosphamide [2-[bis (2-chloroethyl) amino]-2H-I, 3, 2-oxazaphosphorinane 2-oxide, 11, N-methylcyclophosphamide (6), isophosphamide [2-(2-~ hloroethylamino)-3-(2-~ hloroethyl)-2H-