We examined the validity of the Brazilian Frequency of Suicidal Ideation Inventory (FSII-Br), an adaptation of the Frequency of Suicidal Ideation Inventory (FSII), in 946 Brazilian undergraduates. Confirmatory factor analysis of the FSII-Br demonstrated a one-factor model accounting for 62.39% of the variance in FSII-Br scores with a good FIT index. Correlation analyses demonstrated that the FSII-Br was positively correlated with both measures of suicide ideation and suicide risk (viz., depressive symptoms, anxious symptoms, and hopelessness), providing construct validity. Thus, the FSII-Br was found to be a promising tool in assessing suicide risk among Brazilian adults.