Several pre-Jurassic tectonic units in NW Turkey are crucial to the current debate regarding the timing and direction of subduction of Palaeotethys, a major ocean that separated Eurasia and Gondwana in Late Palaeozoic–Early Mesozoic times. The most critical unit is the Karakaya Complex, a deformed, low-grade assemblage of oceanic origin which comprises a NW-verging, SE-dipping stack of tectonostratigraphic units, here interpreted as a Palaeotethyan accretionary complex. The units display lithologies consistent with origins in seamount, trench, abyssal and rifted carbonate platform settings. Clastic basin sequences developed on top of the complex. Other relevant tectonostratigraphic units in the area include ultrabasic rocks of supra-subduction zone affinity, which tectonically overlie Permian carbonate platform units with intervening metamorphic soles and mélanges. Restored structural trends suggest the presence of a southward-dipping Palaeotethyan subduction zone bordering Gondwana-related units during the Late Permian–Triassic. This was probably additional to more important regional northward subduction along the southern margin of Eurasia from the Eastern Mediterranean to the Himalayas.