Germinating sporidia (basidiospores) of Puccinia graminis were cytologically examined during nuclear division (mitosis) to determine the chromosome no. Studies at metaphase showed a haploid no. of 6 for this organism. Prophase chromosomes were united to form a continuous chain. Limits of individual chromosomes could not be seen at this stage. At metaphase, what were apparently residual terminal attractions were observed, the 6 chromosomes appearing as 3 loose pairs. The possibility of a basic chromosome number of 3 for this sp. is discussed.