Some individuals show abnormal reactions to extreme fear and life-threatening situations, including tonic immobility (TI) and peri-traumatic dissociation (PTD). We aimed to investigate the association of TI and PTD with posttraumatic stress disorder (PTSD) in women who experienced sexual violence and the risk factors for PTD occurrence. We compared PTSD severity in 86 young adult women with PTSD after a sexual violence exposure grouped according to the presence of PTD and TI. In addition, we investigated whether PTD is associated with depression and anxiety symptoms and assessed potential risk factors for PTD reaction. We found a significant positive correlation between PTSD severity and PTD occurrence ( R2 = .132; p = .001). PTD was also positively correlated with all clusters of PTSD symptoms except the Clinician-Administered PTSD Scale avoidance cluster ( p = .058). PTD was strongly correlated with anxiety ( R2 = .619; p < .001) and depressive symptoms ( R2 = .547; p < .001). Multiple logistic regression showed that history of physical abuse (odds ratio [ OR]: 1.386; p = .011) and sexual abuse ( OR: 1.947; p = .004) during childhood were associated with PTD occurrence. Other risk factors for PTD were having less years of study ( OR: 0.216; p = .016) and lower income ( OR: 7.403; p = .028). TI measures were available for a subsample of 29 women. We found no association between TI and PTSD severity. PTD, but not TI, is significantly associated with more severe PTSD, depressive, and anxiety symptoms. Less-educated women with a history of childhood abuse and a lower income are at risk of PTD occurrence during a sexual violence episode.