A substantial number of victims of sexual assault refrain from disclosing to others the victimizing episode and its emotional consequences. A prospective study (n = 36 rape victims reporting theirvictimization to the police) and a retrospective study (n = 33) were conducted to examine the determinants of postponed disclosure and its impact on persistent problems. In the prospective study the time interval between trauma and disclosure was at most one month. In the retrospective study 33 percent postponed disclosure for two years or more. Both studies revealed that postponed disclosure is associated with type of perpetrator: Victims of intimate perpetrators were more inclined to postpone reporting than victims of unknown perpetrators. Postponed disclosure predicted health problems in both studies. In the prospective study postponed disclosure predicted frequency of visits to the doctor and use of medication. Initial feelings of numbness contributed to the use of medication as well. In the retrospective study postponed disclosure predicted psychosomatic complaints and use of medication, even when the time between the assault and the interview was taken into account. Type of perpetrator did not moderate the correlation between postponed disclosure and health problems. Some implications for victim support will be discussed. © 2000, College of Health and Human Sciences. All rights reserved.