Thidiazuron (TDZ), a cytokinin-like plant growth regulator, plays an important role in promoting microtuberization in potato. The present study evaluated the effect of TDZ at 0.5, 1.0, and 2.0 ppm on the growth and microtuberization of potato under controlled in vitro conditions using genetically uniform plants. TDZ application significantly suppressed vegetative growth, with plant height, number of nodes and leaves decreasing progressively as TDZ concentration increased. In contrast, TDZ markedly enhanced the microtuberization process. The highest concentration (2.0 ppm) produced the greatest percentage of microtuberizing plants (77.67%), compared with 43.50% in the control, and significantly increased microtuber fresh weight (40.33 mg) and diameter (4.59 mm). Although the number of microtubers per plant increased slightly with increasing TDZ concentration (1.10 at 2.0 ppm versus 0.42 in the control), differences among TDZ treatments were not statistically significant. The results demonstrate a dose-dependent effect of TDZ, where higher concentrations suppress vegetative growth while promoting microtuber initiation and enlargement. Among the concentrations tested, 2.0 ppm TDZ was the most effective for enhancing microtuber production and quality, suggesting its potential application in efficient in vitro seed potato production systems.