The objective of this research was to assess the impact of substitution wheat flour (WF) with psyllium (plantago ovate) seed powder (PSP) at 0, 3,6, and 9% levels on the chemical, rheological and organoleptic properties of  flour, doughs and produced biscuits. The  substitution of WF with PSP significantly increased the contents of crude fiber, ash, protein, fat from 0.58,1.91,6.92 and 15.27%,respectively for control to 1.39,2.28,7.7 and 15.52%, respectively for biscuit sample produced from flour blend that contains 9%PSP, whereas it decreased the corresponding carbohydrates content  from 70.76% to 68.23%.The results showed that the Partial substitution of WF with PSP increased water absorption, arrival time and dough development time, while decreased dough extensibility. Also, the substitution wheat flour with (PSP) led to increment of dough elasticity and energy. The results illustrated that protein content was increased from 6.92% for control to 7.54, 7.62 and 7.70% for 3PSP%, 6PSP% and 9PSP%, respectively. The same trend was also noted with crude fiber content which was increased from 0.58 % for control to0.78,1.16 and 1.39%for 3PSP%,6PSP% and9 PSP%, respectively . The substitution of WF with PSP resulted in decreasing the diameter of biscuit from   4.36 cm for control to 4.22, 4.10 and 4.06 cm for 3%, 6% and 9%PSP, respectively. The substitution of WF with PSP adversely affected all sensory properties of biscuit, since it decreased with increasing the substitution level. The results it could be noted that biscuit sample formulated with substituting WF with 9% PSP was had the lowest sensorial value for all sensory properties but still acceptable.