en فیزیک درمانی Physiotherapy پژوهشي Original Research Articles <strong>Objectives</strong>: To compare the efficacy of balance exercises in the aquatic and Non-aquatic environments compared with control in patients with grade 2 or 3 knee Osteoarthritis (OA).<br> <strong>Methods</strong>: For this single-blind, randomized control trial study, 43 women with mild to moderate knee OA were recruited through a simple non-probability sampling method. They were randomly assigned to the aquatic balance exercise group (n=15), Non-aquatic balance exercise group (n=15), and a control group (n=13). The intervention programs comprised aquatic and Non-aquatic balance training. Fall risk, the primary outcome, was measured by the Biodex balance system before and after the intervention. One-way ANOVA and paired sample t-test were used for analyzing data.<br> <strong>Results</strong>: After 4 weeks training, the Mean&plusmn;SD fall risk score significantly decreased from 3.49&plusmn;1.14 to 2.59&plusmn;1.22 (P<0.001) in the aquatic balance training group, from 3.21&plusmn;0.62 to 2.19&plusmn;0.62 (P<0.001) in the Non-aquatic balance training group, and from 3.77&plusmn;1.13 to 3.17&plusmn;1.22 (P<0.001) in the control group. Regarding between-group comparisons, we found significant differences between the Non-aquatic balance training group and the control group (P=0.03).<br> <strong>Discussion</strong>: Despite the environment, the balance exercise program significantly improved fall risk scores among patients with grade 2 or 3 knee osteoarthritis.&nbsp;<span dir="RTL"></span><span dir="RTL"></span> Fall risk, Knee osteoarthritis, Aquatic exercise, Balance 343 350 http://irj.uswr.ac.ir/browse.php?a_code=A-10-1166-1&slc_lang=en&sid=1 Farzaneh Hajmohammadi pt.farzaneh24@gmail.com 0000-0002-1160-1587 No Deptment of Physical Therapy, Zahedan University of Medical Sciences, Zahedan, Iran. Mohammad Hosseinifar fardash_s@yahoo.com 0000-0003-1866-8642 Yes Deptment of Physical Therapy, Zahedan University of Medical Sciences, Zahedan, Iran. Asghar Akbari akbari_as@yahoo.com 0000-0002-2993-4574 No Deptment of Physical Therapy, Zahedan University of Medical Sciences, Zahedan, Iran. Fatemeh Ghiasi f_ghiasi_p@yahoo.com 0000-0001-9849-6670 No Deptment of Physical Therapy, Zahedan University of Medical Sciences, Zahedan, Iran. Hassan Namvar hassan753@yahoo.com 0000-0003-2261-7506 No Deptment of Physical Therapy, Zahedan University of Medical Sciences, Zahedan, Iran. Ahmadreza Askari Ashtiani ahmadaskary@gmail.com 0000-0002-0210-9005 No Deptment of Physical Therapy, Zahedan University of Medical Sciences, Zahedan, Iran.