Testicular adrenal rest tumours (TARTs) are benign ACTH-dependent tumours that occur in males with congenital adrenal hyperplasia (CAH) and if left untreated can destroy testicular tissue. Corticosteroid suppressive treatment could result in the regression of these testicular tumours. We present a patient with bilateral large TARTs as a consequence of poor compliance to treatment and follow-up for his CAH, who consequently had to have bilateral orchidectomies and prosthesis replacement. CONCLUSIONS TARTs are frequently seen in males with CAH, and can be misdiagnosed as primary testicular cancer.Patient compliance to treatment and follow-up are necessary to reduce the risk of testicular damage as a result of TARTs in patients with CAH.Boys with CAH should have periodic ultrasonographic screening from before adolescent age for early detection of TARTs.Regular monitoring of renin, 17-hydroxyprogesterone and androgens levels is required to assess corticosteroid suppressive treatment.Patients with CAH should be offered psychological support and information concerning CAH support groups.