Rosemary (Rosmarinus officinalis; RM) and thyme (Thymus vulgaris; TV) are used as remedies. We designed this work to investigate the preventive effect of aqueous extracts of RM or TV on the gentamicin (GM)-induced hepatotoxicity and abnormalities of lipid profile in rats. Both plant extracts exhibited an in vitro antioxidant activity as determined by the 1,1-diphenyl-2-picrylhydrazyl assay. Radical scavenging activity for TV extract was 48.7% and for RM extract was 25.6%. Polyphenolic determination by high-performance liquid chromatography for both extracts revealed that catechin, coumarin, cinnamic acid and rutin were detected in both extracts. RM extract had higher values than TV extract in all except rutin. Ferulic acid and quercetin were also detected in TV extract and sinapic acid and oleuropein were detected in RM extract. In rats given GM intraperitoneally for 10 days and coadministered either RM extract or TV extract orally, both aqueous extracts demonstrated similar hepatoprotective effects manifested by approximate normalization of plasma liver enzymes (AST and ALT), bilirubin level and total protein concentration compared with the group given GM only. Abnormal lipid parameters and raised hydrogen peroxide levels were ameliorated by both extracts. Pancreatic lipase activity was markedly reduced by RM extract. Also, the atherogenic index value was significantly reduced by both extracts as compared to that of GM group. DNA fragmentation analysis confirmed tissue damage by GM and its amelioration by the extracts. These findings suggest that RM and TV extracts could be helpful in ameliorating some aspects of gentamicin toxicity.