Background To date, the significance of factors purported to be associated with subacromial shoulder impingement (SSI) and what differences, if any, are present in those with SSI compared to a matched asymptomatic population has not been identified. Gaining information about differences between people with SSI and asymptomatic people may direct clinicians towards treatments that impact upon these differences. Objective Compare the assessment findings of factors suggested to be associated with SSI; passive posterior shoulder range, passive internal rotation range, resting cervical and thoracic postures, active thoracic range in standing and scapula positioning between cases experiencing SSI and a matched asymptomatic group (controls). Study design Case Control Study. Method Fifty one SSI cases and 51 asymptomatic controls were matched for age, gender, hand dominance and physical activity level. The suggested associated factors were measured bilaterally. Independent t-tests were used to compare each of these measurements between the groups. Any variables for which a significant difference was identified, were then included in a conditional logistic regression analysis to identify independent predictors of SSI. Results The SSI group had significantly increased resting thoracic flexion and forward head posture, as well as significantly reduced upper thoracic active motion, passive internal rotation range and posterior shoulder range than the matched asymptomatic group. No independent predictors of SSI were identified in conditional logistic regression analysis. Conclusion Thoracic posture, passive internal rotation range and posterior shoulder range were significantly different between cases experiencing SSI and a matched asymptomatic group. Level of evidence Level 3a.