The objective of this study was to investigate the influences of zinc oxide nanoparticles (ZONPs) on the anxiety-related behaviors of male albino rats. Because of the sexual differences found in the anxiety related disorders, thirty-six male albino rats 40-days old weighed from 130 to 150 g and divided into three groups; group I served as a control, groups II and III were subjected to daily intraperitoneal injection of ZONPs (30 mg/kg or 60 mg/kg, respectively) for 5 days sequentially. Each treatment contained four replicates of 3 rats each. Eight rats per treatment (i.e.2 rats/replicate) were randomly taken and marked with green livestock spray for behavioral observation and anxiety testing on same day of injection. Elevated plus maize, open field, forced swimming, tail suspension tests were used for anxiety testing. Afterwards, the rats were sacrificed, and the histopathological evaluation of brain tissue was done. The results showed that the intraperitoneal injection of ZONPs reduced the standing behavior, climbing time of the forced swimming test, and increased the sleeping behavior, immobility time of the forced swimming test and agitation and immobility time of the tail suspension test (P < 0.05); while the ZONPs had no effects on alert activities, open field test, and elevated plus maize test (P > 0.05) in ZONPs injected groups. In addition, ZONPs induced necrosis of the nerve cells in cerebral cortex and the Purkinje cells in cerebellum.