To investigate potential changes in the North Atlantic intermediate water-mass configuration across the Mid-Pleistocene Transition (MPT; approx. 550-1200 ka) we utilize d18O and d13C records obtained on the deep thermocline-dwelling foraminifera Globorotalia crassaformis and benthic Cibicidoides wuellerstorfi from mid-latitude International Ocean Discovery Program (IODP) Site U1313. Analyses were done at the Institute of Earth Sciences, Heidelberg University on an MAT 253 with a KIEL IV device. Scientific target was the reconstruction of intermediate water mass variabily, especially with regard to the establishment of a Glacial North Atlantic Deep Water (GNAIW) - like water mass.