The effects of cold cathode fluorescent lamps (CCFL) as a light source on the photoautotrophic growth of Crassulacean acid metabolism (CAM) Phalaenopsis orchid plantlets in vitro have been studied by using the film culture vessel “Vitron” with sugar-free modified Kyoto medium under 3,000 μmol mol^-1 CO₂. To clarify the optimum blue to red light ratio of CCFL, plantlets were cultured under CCFL with either 90, 80, 70 or 60% red + 10, 20, 30, 40% blue, respectively; greatest shoot and root fresh weights were observed in plantlets grown under 80% red + 20% blue CCFL. The plantlets grown under this blue to red ratio CCFL also showed greater leaf length, shoot dry weight, and root fresh and dry weights than those grown under plant growth fluorescent lamps (HFLs). Attempts were also made to examine the effect of CO₂ enrichment higher than 3,000 μmol mol^-1 under CCFL on the growth of in vitro plantlets. The growth of plantlets was remarkably enhanced under 5,000 μmol mol^-1 CO₂ compared to that of plantlets cultured under 3,000 μmol mol^-1 CO₂. By examining the diurnal changes in CO₂ concentration inside the Vitron vessel with Phalaenopsis plantlets cultured under 5,000 μmol mol^-1 a typical CAM CO₂ gas pattern was not evident, but rather that of typical C₃ type. Our study indicates that the CCFL light source is effective for Phalaenopsis growth in vitro while high CO₂ (5,000 μmol mol^-1) enrichment under CCFL has a positive effect on the production of clonal Phalaenopsis plantlets in commercial tissue culture laboratories.