Mercury is a naturally occurring heavy metal which is used in manufacturing of thermometers and electrical switches. It is also present in dental amalgam fillings and skin lighting creams. The present work was designed to study the histological, histomorphometric and ultrastructural changes following administration of mercuric chloride on the kidney of the adult male albino rat, as well as, the possible protective role of verapamil if used concomitantly or after exposure to mercuric chloride. It was concluded that mercuric chloride causes significant alterations of the renal histological structure, and these alterations are irreversible after withdrawal of mercuric chloride. Concomitant administration of verapamil with mercuric chloride affords a partial protection with reduction of the inflammatory reaction.