This study assesses the contribution of capital gains tax to internally generated revenue of Adamawa State 2000 – 2022. Ex-post facto research design was adopted by the study. The study used secondary data and the data were collected from Adamawa State Board of Internal Revenue annual reports and accounts. The study used descriptive statistics and ordinary least square regression in data analyses and testing of hypothesis. The data was run with the aid of Eview 9.0. The result of the study shows that capital gains tax has positive and significant relationship with internally generated revenue. The study recommended based on the finding that government should increase the rate of capital gains tax in order to improve the revenue generated from capital gains tax in order to finance government activities.