Twenty-one non-anthraquinones constituents were isolated for the first time from an ethanol extract of the roots of Knoxia valerianoides by using a combination of various chromatographic techniques including column chromatography over silica gel, Sephadex LH-20, and reversed-phase HPLC. Their structures were identified by their physical-chemical properties and spectroscopic analysis including NMR and MS. The compounds include ten triterpenoids: ursolic acid (1), oleanolic acid (2), 2-oxo pomolic acid (3), pomolic acid (4), maslinic acid (5), rotungenic acid (6), tormentic accid (7), rotundic acid 3,23-acetonide (8), arjungenin (9), and 2alpha, 3beta, 19alpha, 23-tetrahydroxy-urs-12-en-28-oic acid (10), four sitosterones: (24R)-24-ethylcholesta-4,22-dien-3-one (11), 3-oxo-4-en-sitosterone (12), 7-oxostigmasterol (13), and 7-oxo-beta-sitosterol (14), two lignans: eudesmin (15) and ciwujiatone (16), one coumarin: cnidilin (17), and four simple aromatic analogues: 5-hydroxymethylenefural (18), 3-hydroxy-4-methoxybenzoic acid (19), benzoic acid (20), and 2-hydroxy-5-methxoycinnamaldehydes (21). In the in vitro assays against human cancer cell lines (HCT-8, Bel7402, BGC-823, A549, and A2780), against deserum and glutamate induced PC12-syn cell damage, and against HIV-1 replication, and inhibiting protein tyrosine phosphatase 1B (PTP1 B), LPS induced NO production in macrophage, and Fe(2+)-cystine induced rat liver microsomal lipid peroxidation, at a concentration of 1 x 10(-5) mol x L(-1), no compound showed activity.