Rice false smut (RFSm) disease caused by Ustilaginoidea virens (Cooke) Takah (teleomorph: Villosiclava virens) has become one of the most destructive rice diseases all over the world. The pathogen is known to produce secondary metabolites i.e. ustiloxins... which are known to be harmful to plant growth, human and domestic animals. This work had taken into consideration the effect of soaking seeds in either the pathogen spore suspension or rice false smut balls cell free extract (RFSBCFE) on seed germination, shoot length and root length of nine rice cultivars. Seed germination % ranged from 78.66 to 98.66 under soaking in spore suspension, however it ranged from 20 to 93.33 when seeds were soaked in RFSBCFE. Soaking rice grains of Sakha 104 in spore suspension, recorded the highest values in shoot and root length (5.23 and 5.80, respectively). While, Super 300, Sakha 108 and Sakha 104 cultivars showed the highest shoot and root length when their grains were soaked in RFSBCFE. Using LC-MS/MS method, five Ustiolxins (A, B, C, D and F) have been detected in RFSBCFE. Finally, toxic effect of using contaminated diets with these smut balls for feeding with five concentrations (0%, 1%, 5%, 10% and 25% (wt/wt)) has been studied on rats. RFSBs were found to pose risks of renal and hepato-toxicity in rats. Since biochemical parameters of liver and kidney functions (urea and creatinine concentration) were severely affected. Likewise, haematological indices were also influenced. On the other hand, the above mentioned lesions were relatively obscure in concentration 1%.