Post-traumatic stress disorder (PTSD) is characterized by intrusions, re-experiencing,avoidance and hyperarousal. These symptoms might be linked to dysfunction in core neurocognitivenetworks subserving self-referential mental processing (default mode network, DMN), detection ofsalient stimuli (salience network, SN) and cognitive dysfunction (central executive network, CEN).Resting state studies in adolescent PTSD are scarce and findings are inconsistent, probably due todifferences in patient symptom severity. Resting state brain activity was measured in 14 adolescentswith severe PTSD and 24 age-matched controls. Seed-based connectivity analyses were used toexamine connectivity between the DMN and the whole brain, including regions from other networks(SN and CEN). The relationships of network properties with symptom dimensions (severity, anxietyand depression) and episodic memory were also examined. Analyses revealed decreased within-DMNconnectivity (between PCC and occipital cortex) in patients compared to controls. Furthermore, within-DMN connectivity (between PCC and hippocampus) correlated negatively with symptom dimensions(severity and anxiety), while increased connectivity (DMN-SN and DMN-CEN) correlated positivelywith episodic memory measures. These abnormal network properties found in adolescent PTSDcorroborate those previously reported in PTSD adults. Decreased within-DMN connectivity anddisrupted DMN-SN and DMN-CEN coupling could form the basis for intrusive trauma recollection andimpaired episodic autobiographical recall in PTSD.