Influence of altitudinal, seasonal and environmental factors on the production of the active principles in Helleborus odorus subsp. laxus (Host.) Merxm. & Pod. - The influence of some factors (altitude, season, environment) on the production of the active principles ofHelleborus odorussubsp.laxus(Host) Merxm. & Pod. is examined. The samples have been taken at different altitudes and from different environments during various phases of the biological-cycle, in an area on the southern border of the Carnia-prealps zone (Friuli-Venezia Giulia). Only the two main active principles present in the hypogeous organs of such entity, hellebrin and saponin (Rf = 0.63), are considered because in previous works it was demonstrated that such secondary metabolites are chemotaxonomic markers for these entities. Quantitative analysis undertaken separately on roots and rhizomes, have shown a connection between variations of hellebrin and saponin (Rf = = 0.63) contents and physical-environmental factors. In particular it has been found that during the activity period of the plant the quantity of the two previously mentioned principles increases according to the altitude. Various anomalous environmental characteristics such as reafforestation, inhabited areas, steep sunny slopes, seemed to increase the production of the two active principles.