This study investigates how hot isostatic pressing (HIP) affects fatigue performance in additively manufactured (AM) Ti-6Al-4V. By varying initial material states through different AM systems and process parameters, limitations of HIP are explored. Results show that fatigue performance depends on the as-built quality of the material. Differences in material attributes like defects or microstructure don’t fully explain performance variations, suggesting other factors may be at play. Additionally, exploring HIP parameters beyond ASTM recommendations reveals improved fatigue performance with reduced temperature and high-pressure treatments.