Libya is country of desert and the arid climate makes it in extreme lack of surface water .Groundwater then bececomes a very important resource to meet the economical and agricultural demand ,which believed to be comparatively much cleaner and free from poliution than surface water , water poliution is a state of deviation from pure condition .whereby its normal function and properties are affected .The present study is amied at assesses the bacteriologcal pollution of ground water samples used for humans and animals at different 11 localities in Tripoli rigion , Libya .This study related to the bacteriologcal analysis revealed high values of toral bacterial count in groundwater samples from both tanks (648.85 cfu/ml)and wells (394.34cfu/ml) than standard count imit (100cfu/ml)for driking water by EPA. Naarly similar values of MPN of coliform (58.00MPN/100ml) and E.coli bacteria (0.20) from both tanks and wells, other than zero number per 100 ml set by WHO .Finally , we did not find pathogenic bacteria as Salmonella and Enterococci bacteria , but there is very littel number of pathognic bacteria as Staphylocooccus aurous (1.50) and Pseudomonas aerugnosa (0.07) isoaled from both tanks and wells samples . Hence ,it was concluded that . This research to analysis the bacteriologcal pollution of grandwater used for hnmans and animals for some different localities of Tripoli , Libya with review to the hygienic standards and suggest an approach for imporing and prevent such contamination . Microbiological lested ground waters samples are good and mostly suitable for domestic uses. the coliform and pathogenic bacterial contamination render this water unsatisfactory for driking purposes unless bacteriologically perfactly treated ,if necessary for consideration for utility.