The objective of this study was to examine the association of pharyngeal lymphoid hyperplasia (PLH), recurrent laryngeal neuropathy (RLN), mucus accumulation (MA) score and tracheobronchial secretion neutrophil percentage (TBS-N) with rider-assessed performance in sport horses. Airway endoscopy scores, tracheobronchial secretion cytology, rider-assessed general impression and willingness to perform were investigated in 171 top-level sport horses.Increased MA appears to be associated with poor willingness to perform in sport horses. Older horses had decreased PLH scores and increased TBS-N. Mucus accumulation scores ⩾3 were associated with increased odds (mean 9.92; upper and lower 95% confidence intervals: 1.5–64.6) of poor rather than excellent willingness to perform. A TBS-N of 20–50% compared with <20% was associated with decreased odds (median 0.11; upper and lower 95% CI: 0.02–0.66) of poor rather than excellent willingness to perform. In addition, horses with an RLN grade ⩾2 had significantly higher odds for giving a poorer general impression and willingness to perform. This finding, however, must be interpreted with caution, since only two horses had significant RLN (grade ⩾3).