Study of the effects of the methanolic extract of Tagetes patula roots on blood pressure led to the isolation of well known citric (1) and malic acid (7) as hypotensive, and pyridine hydrochloride (4) as hypertensive constituents of the plant along with a new constituent, 2-hydroxy, 5- hydroxymethyl furan (9). Citric acid and malic acid caused 71% and 43% fall in Mean Arterial Blood Pressure (MABP) of rats at the doses of 15 mg/kg and 30mg/kg respectively while pyridine hydrochloride produced 34% rise in the MABP of rats at the dose of 30mg/kg. $LD_{50};and;LD_{100}$ of citric acid in mice have been determined as 545 mg/kg and 1000 mg/kg, respectively.