Self-harming has been reported among prison inmates globally; it often starts with the urges. Empirical evidences from developed countries have shown Dialectical Behavioural Therapy (DBT) to be efficacious in reducing self-harm urges. There appears to be no evidence of the use of DBT in Nigeria either for research or therapeutic purposes. This study therefore tested the efficacy of DBT Nigeria. A total of 135 inmates randomly selected from Uyo Prison participated in the study which adopted pre-test post-test quasi-experimental design. Inmates’ Self-Harm Urges Scale, modified DBT, and Diary Cards were used to gather data. Results showed that inmates who were exposed to DBT continuously reported reduced self-harm urges post-test and 3-months follow-up stages. They also showed lower self-harm urges at post-test and follow-up stages compared to those who did not participate in DBT. It was recommended that DBT be used as a psychological adjunct in prison inmates’ rehabilitation
