In this study, cytogenetic effects of 99 technetium (99 Tc) on meristematic cells of root tips belonging to Vicia faba L. have been investigated. Seeds of the plant were prepared and kept in 99 Tc standard for different time periods: 1/12, 1/4, 1/2, 1, 2, 3, 4, 5, 6 and 12 h. Seeds treated with 99 Tc were sprouted and the root tips obtained were prepared for microscopic examination. Some abnormalities e.g. chromosome breaking, chromosome dispersion, bridge chromosomes, chromosome adherence and ring chromosomes were observed. Abnormalities seen for each treatment depended on the time period. The variety and number of abnormalities usually increased with increased treatment time. The results obtained were evaluated statistically.