Cobalt ferrite (CoFe2O4) nanoparticles have been reported to be potential materials for applications in medical sciences such as MRI cancer diagnostics, and drug delivery in cancer treatment. Their magnetic properties also make them suitable as electronic materials. The promising applications of CoFe2O4 NPs suggest the possibility of the materials to be released into the environment. The possible adverse effects on animals and food plants have become concerns. While the information about the effect of some nanomaterials on food plants are available, the effect of CoFe2O4 NPs on plant had never been reported. To investigate the effect of CoFe2O4 NPs on tomato plants