BACKGROUND: Despite the similar knee osteoarthritis (KOA) prevalence among races and ethnicities, Hispanic patients with KOA are 30%-40 % less likely to receive treatments compared with their White counterparts. Tai Chi (TC) could be an accessible and affordable intervention for Hispanic individuals with KOA. This case series explored the effect of four optimal TC forms (OTC) on reducing KOA pain in Hispanic individuals. METHODS: Seven Hispanic adults with mild to moderate KOA were recruited. Their knee pain level during walking was evaluated before and after a two-week OTC training using the Visual Analog Scale and compared between assessments. RESULTS: The 2-week OTC training course was well received by our participants. The training reduced pain with a large effect size (4.14 ± 1.21 vs. 1.29 ± 1.70 cm, p <
0.027, Wilcoxon's r = -0.833). CONCLUSION: Our pilot results suggested that the 2-week, 4-form-based OTC program can significantly reduce the knee pain in Hispanic people with KOA. Our OTC program appears to be about 20% more effective in reducing knee pain than the existing TC-based program, which uses 10 TC forms over 12 weeks (1.27 vs. 1.06 in Hedge's g). The findings implied that the OTC program could be a promising alternative paradigm for Hispanic people with KOA to lower their pain. This case series could provide vital information for the design and execution of future large-scale and rigorous clinical trials to further test the effects of the OTC program in altering pain for Hispanic people with KOA. CLINICALTRIALS GOV REGISTRATION ID: NCT03621631.