A highly sensitive fluorometric procedure for determination of zidovudine is described. The procedure depends on the interaction between zidovudine with 7-hydroxy-4-methylcoumarin where a fluorophore of high fluorogenic activity is produced exhibiting wavelengths of maximum excitation and emission of 340 and 450 nm, respectively. The procedure is used for the determination of zidovudine in human plasma in the range of 2-8 ug ml^-1 in a rectilinear relationship .The mean percentage recoveries were 99. 193± S.D 1.928 in case of bulk drug while it was 99.832± S.D 1.809 in case of 7 concentrations in human plasma.