Background: clarithromycin is a semisynthetic macrolide antibiotic, exhibits broad-spectrum activity against gram-positive and gram-negative aerobes. Macrolides are bacteriostatic antibiotics that inhibit protein biosynthesis via reversible binding to the bacterial 50S ribosomal subunit. Macrolides are able to cross placenta and reach the fetus.
Aim of the work: the present study is focused on evaluating the effects of antimicrobial drug, clarithromycin on the kidneys of pregnant rats.
 Material and methods: clarithromycin is orally given to the treated groups of the pregnant rats once daily at different periods of gestation by gastric tube at a dose of 45 mg/kg/day. The excised kidneys were dissected, processed and stained with H & E, PAS, Masson's trichrome, Feulgen reaction and anti-CD68 immunohistochemical stain then followed by morphometric measurements and statistical analysis. The kidneys were also preserved for DNA fragmentation assay.
Results: this study revealed that clarithromycin administration especially to pregnant rats showed different histopathological and histochemical changes in kidney tissues and cellular DNA. Also immunohistochemical anti-inflammatory marker CD68 showed positive reactivity in all treated groups.                               
Conclusion: The presence of histopathological and histochemical changes revealed nephrotoxicity in the pregnant rats after administration of the antimicrobial drug, clarithromycin.