Gout is clinically characterized by episodes of monoarthritis, which not only typically affects the peripheral joints but also occasionally affect the axial joint, such as the sacroiliac joint (SIJ), and often mimics spondyloarthritis (SpA). Two cases of gout mimicking SpA are presented in the current paper. One patient was a 32-year-old man with a history of asymmetrical oligoarthritis of ankle and metatarsophalangeal joints (MTPJ). He had left gluteal pain for 2 weeks. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed the bone erosion of the left SIJ. T1-weighted MRI showed hypointense T1 and hyperintense T2 signals of the left SIJ. The other patient was a 24-year-old man with left back pain and hip pain for 4 months and intermittent fever for 3 months. He had a history of gout for 3 years. Both patients underwent CT-guided sacroiliac biopsy, and monosodium urate (MSU) crystals were shown by polarized microscopy. Gout can often mimic SpA and seldomly affects the SIJ. Thus, its correct diagnosis and adequate therapy can halt the development of such damaging complications.