Bioerosion is rare in large benthic foraminifera (LBF) in the Eocene of Ziarat Formation. Three bioerosion ichnotaxa have been identified, including more common Trypanites isp. and Entobia isp., and rare Meandropolydora sulcans. The rare bioerosional traces in LBF tests support the scenario of an oligotrophic nutrient regime at the studied interval. The sedimentation rate may have also been among the controls on the bioerosion of LBF in the Middle Eocene of Iran, but the oligotrophic nutrient regime likely had a stronger effect. The bioerosion of LBF tests during the Middle Eocene Climatic Optimum (MECO) was rather low or at maximum moderate, suggesting that an oligotrophic nutrient regime could compensate for the increase in bioerosion caused by ocean acidification and warming.