Trigonella foenum-graecum (Family: Fabaceae) a well-known medicinal plant grows in nature and is cultivated in Sudan. It is having properties of lowering blood sugar level, anthelmentic, antibacterial, anti-inflammatory, antipyretic, and antimicrobial. This study was carried out to evaluate antigiardial activity (Giardia lamblia) and cytotoxicity (MTT assay) of ethanol extract of T. foenum-graecum (seeds). The ethanol extracts of T. foenum-graecum (seeds) was screened for its antigiardial activities (Giardia lamblia) and screened for their cytotoxicity using 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), was obtained from T. foenum-graecum (seeds) ethanol extract which exhibited 100% mortality within 96 h, at a concentration 500 µg/ml; this was compared with Metronidazole which gave 96% inhibition at concentration 312.5 µg/ml at the same time. In addition cytotoxicity (MTT assay) with different concentration (500, 250 and 125 ppm) in comparison to triton-x100 (the reference control) which verified the safety of the examined extract with an IC50 less 100 μg/ml. In conclusion, these studies prove the potent activity of T. foenum-graecum (seeds) against G. lamblia trophozoites in vitro with verified safety evidence for use.