Today, we are exposed to heavy metals directly or indirectly, and their long-term accumulation has numerous side effects. Anomalies that may occur especially at the gene level are worrisome as they can be transmitted to the next generation. For this reason, a practical and instructive study on the effects of heavy metals was planned in a short time. Accordingly, the onion (allium cepa) used in our homes was left to germinate a week ago. On the day of the study, root tip samples other than the control group were exposed to a solution containing CuSO4 (0.05 g/100 ml-Copper sulfate) for 24 hours and at the end of the period, preliminary preparations were completed and staining was performed. Chromosomal anomalies were observed and photographed using a light microscope. Thus, heavy metals and their effects were discussed and information was given about the necessary protection methods.