Phaius tankervilleae ‘alba’ is a highly ornamental orchid species listed as a rare and endangered species in several countries. To develop an efficient in vitro propagation method, this study investigated the effects of light quality on seed germination and protocorm development. Seeds were cultured on VW medium under various light conditions, including darkness, cool white LED, cool white, warm white, blue, red, green and yellow fluorescent lamps, for three months. The highest germination rate (91.3%) was observed under blue fluorescent light, followed closely by red fluorescent light (86.0%), with no significant difference between the two. Notably, blue fluorescent light also promoted the highest percentage of advanced-stage protocorms (stage 3+4) at 28.3%. Although green fluorescent light resulted in a lower germination rate (61.0%), it induced a comparable rate of advanced-stage protocorms (25.0%), not significantly different from the blue light treatment. In contrast, seeds cultured in darkness exhibited the lowest germination rate (18.7%) and the highest proportion of dead protocorms (12.3%). Protocorms' mortality was also observed under cool white, green and yellow fluorescent lights. The results indicate that light quality significantly affects seed germination and protocorm development in P. tankervilleae ‘alba’, with blue fluorescent light being the most effective for promoting successful in vitro propagation. Keywords: light quality; orchid; terrestrial orchid; light spectrum; VW medium.