St. John's Wort (Hypericum perforatum L.), a perennial from Hypericaceae, is one of the highly esteemed medicinal plants since ancient times. The tops are used for its soothing, calming antidepressant effects, wound healing, antispasmodic, and antiviral effects. Recently it has been found to be a natural substitute for “PROZAC™”. So far, most of the commercial supply of St. John's Wort originates from wild collections. Five different cultivars of Hypericum perforatum originating from Germany (`Due-1', `Due2') Canada (`Quebec'), United States (`TLF-1'), and Russia (`Russia') were grown under commercial organic cultivation. H. perforatum of Canadian origin (Quebec) and `TLF-1' from the United States (Washington and Oregon) were of a recent selection, while the German (Due-1, Due-2) and Russian cultivars were selected for higher yield and better concentration of the active constituents (essential oil, hypericin, and other related flavonoids). Seeds obtained from these cultivars were directly sown in the field, using animal manure, in Trout Lake Farm, Wash. There was a significant difference among the cultivars in morphology, flowering period, yield, and content of the essential oil. Cultivars Due-1, Due-2, and Russia showed an erect growth, with uniform flowering time and pattern, indicating the suitability of these cultivars for mechanical harvesting and better exposure of the flowers to sunlight. The highest herb yield was obtained from `TLF-1', while the lowest was obtained from `Quebec'. Cultivar TLF-1 came to flowering the latest, while `Due-1' was recorded to flower earliest and had the lowest shoot yield. The essential oil content of `Due-1', `Due-2' and `Russia' was significantly higher than `Quebec' and `TLF-1' cultivars.