Idiopathic retroperitoneal fibrosis (IRPF) is a rare disease characterized by a retroperitoneal inflammatory proliferative fibrosing process. Hashimoto's thyroiditis is the most common inflammatory condition of the thyroid gland; and is a frequently-occurring autoimmune disorder manifesting predominantly in middle-aged women. We report a rare association of IRPF with Hashimoto's thyroiditis in a 67-year-old man demonstrating good response to steroid therapy.