General population-based survival statistics for primary malignant brain or other central nervous system (CNS) tumors do not provide accurate estimations of prognosis for individuals who have survived for a significant period of time. For these persons, the use of conditional survival percentages provides more accurate information to estimate potential outcomes. Using information from the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) program from 1995 to 2012, conditional survival percentages were calculated for 1 or 5 years of additional survival for all primary malignant brain and CNS tumors overall and by gender, race, ethnicity and age. Rates were calculated to include 1, 2, 3, 4, 5, 10 and 15 years post diagnosis. Conditional survival was also calculated in intervals from 1995-2004 to 2005-2012, to examine the potential effect that the introduction of new treatment protocols may have had on survival rates. The percentage of patients surviving one or five additional years varied by histology, age at diagnosis, gender, race and ethnicity. Younger persons (age <15 years at diagnosis) had higher conditional survival percentages for all histologies as compared to all histologies in older patients (age ≥15 years at diagnosis). The longer the amount of time post-diagnosis of a malignant brain or other CNS tumor, the higher the conditional survival. Younger persons at diagnosis had the highest conditional survival irrespective of histology. Use of conditional survival rates provides relevant additional information for patients and their families, as well as for clinicians and researchers, and helps with understanding prognosis.