This Ph.D thesis deals with the phytochemical studies on two species of the genus Heliotropium of Pakistani origin. The thesis is divided in to two parts: Section A deals with the phytochemical studies on Heliotropium eichwaldi that have led to the isolation of a novel compound Furo furan lactone [(4a,6b-dihydroxy-5-(hydroxymethyl)-2a-isopropyl-2-methylhexahydro- 4H-1,3,6-trioxacyclopenta[cd]pentalen-4-one)] 1. The structure elucidation of compound 5 was done by spectroscopic means and confirmed by X-ray crystallographic technique [Firdous S. et al., 2012 a]. In addition to that three known compounds, Heliotrine 4, β-Sitosterol 3-O- β-D-glucopyranoside 5 and β-Sitosterol 6 have also been isolated and characterized from this species. Section B of the thesis describes work on a related species Heliotropium ophioglossum. The phytochemical investigation on this plant resulted in the isolation and characterization of two new compounds Ophiamide-A (2S,3S,4R,6E,2̍R)-2-[2''-hydroxypentacosanoylamino]-octadec-6-ene-1,3,4-triol 42 and Ophiamide-B 1-O-β-D-glucopyranosyl-(2S,3S,4R,6E,2̍R)-2-[(2''-hydroxypentacosanoylamino]-octadec-6-ene-1,3,4-triol 43. These two new compounds exhibited potent urease inhibitory activity [Firdous S. et al., 2012 b]. In addition to this eight known compounds have also been isolated and identified for the first time from this species. The known compounds isolated from H. ophioglossum are 2''(4''''-Hydroxyphenyl)-ethyl Lignocerate 44, Glycerol Monopalmitate 45, Methyl 2,4-Dihydroxy Cinnamate 46, 4-Hydroxycinnamic acid 47, 4-Hydroxybenzoic acid 48, 1-Octacosanol 49, β-Sitosterol 3-O- β-D-glucopyranoside 5 and β-Sitosterol 6. The structure elucidation of all compounds involved modern spectroscopic techniques such as MS, 1H and 13C-NMR, IR and UV.