The effect of normal and continuous day light (White lamps 3000 Lux) as well as, cold  treated or untreated seeds on propagation of Hypericum perforatum L. In vivo and In vitro were studied. It was found that: In vivo, the cold treated seeds with 4°C for 30 days before cultivation  under continuous light showed the best results, i.e. higher germination percentage; plant height (cm); greater  number of branches/plant; fresh and dry weight (gm/plant) and dry matter content (%) as compared with untreated seeds which cultured either under normal or continuous day light. In vitro studies, the obtained plantlets from cultivation of cold treated seeds on MS-agar medium supplemented with 0.05 mg/l NAA + 0.5 mg/l BA, and incubated at 26 ± 1°C for three months then, transferred into greenhouse under continuous day light, showed the best results on obvious determinations than untreated seeds or treated seeds and cultured under normal day light. Propagation of Hypericum perforatum L In Vitro  showed better results than In Vivo.