ABSTRACT: Ostracod faunas from Upper Permian to Lower Triassic shelf deposits of Northwestern Iran were investigated with respect to their stratigraphical range, palaeoecology and extinction patterns. Faunal changes caused by sea level rise are recorded in the lower Dzhulfian, lower and upper Dorashamian. The global End-Permian mass extinction event is recorded in NW Iran by a complete ostracod faunal turnover in the uppermost Dorashamian (C. meishanensis – H- praeparvus Zone) and disappearance of the deep neritic communities. The lithofacies and micropalaeontological data show that there was no shelf anoxia in Northwest and Central Iran during the P/T Boundary (PTB) interval and earliest Triassic. Ostracod extinction patterns in Iran indicate that the Late Permianmass extinction was not directly effected by the onset of shelf anoxia. According to quantitative palaeobiogeographical results faunal exchange of neritic ostracods in the Palaeo- andNeotethyswas very limited during the Late Permian.Occurrences of closely related species at the PTBand in the lowermost Triassic of Iran (Sandandaj-Sirjan region), Taurus and South China however, suggest that these regions were connected by shelf migration routes during this time interval.