Side effects of synthetic drugs has led to more extensive use of medicinal plants. A variety of several herbal medicines have been produced recently. St.john's wort is an important one in the pharmaceutical industries of developing countries. St.john's wort cultivation has been introduced to and developed in our country during recent years. This investigation was carried out for studying the e1Iects of different levels of nitrogen and phosphorus fertilizer on the plant A complete randomized block design with three replicates was used. Hypericin content was measured by spectrophotometry and on the basis of Hungarian standards. Chlorophyll content was measured by Espad - 502 Chlorophyll meter. Results show that the highest fresh yield in the first harvest (1597.5 glm2) belongs to N250PO treatment and the lowest (l187.5 glm2) to control treatment. Results of fresh yield of 2nd harvest and dry yield of first harvest show no significant difference. All fertilizer treatments increased the number of flowering stems, hypericin and chlorophyll content of the herb as compared to control. There is a positive correlation observed between hypericine content of the herb and no of flowering stems as well as between chlorophyll content and hype:ricin level (r2=0.84 and r2=0.74 respectivt_ly ).
)