Objectives: To assess the efficacy of fine focal spot imaging in calcification beam-hardening artefact reduction and vessel clarity on CT abdominal angiography (CTAA). Methods: Adult patients of any age and gender who presented for CTAA were included. Thirty-nine patients were examined with a standard focal spot size (SFSS) of 1 ? 1 mm in the first 3 months while 31 consecutive patients were examined with a fine focal spot size (FFSS) of 1 ? 0.5 mm in the following 3 months. Vessel clarity and calcification beam-hardening artefacts of the abdominal aorta, celiac axis, superior mesenteric artery, inferior mesenteric artery, renal arteries, and iliac arteries were assessed using a 5-point grading scale by two blinded radiologists randomly. Results: Cohen?s Kappa test indicated that on average, there was substantial agreement among reviewers for vessel wall clarity and calcification artefact grading. Mann-Whitney test showed that there was a significant difference between the two groups, with FFSS performing significantly better for vessel clarity (U, 6481.50; p <0.001; r, 0.73) and calcification artefact reduction (U, 1916; p <0.001; r, 0.77). Conclusion: Fine focus CT angiography produces images with better vessel wall clarity and less vessel calcification beam-hardening artefact. Key Points: ? Focal spot size affects the spatial resolution of a CT system. ? Fine focus CTAA produces images with improved vessel wall clarity. ? Fine focus CTAA is associated with fewer calcification beam-hardening artefacts. ? Fine focus CTAA may improve accuracy in assessment of luminal stenosis. ? 2014, European Society of Radiology.