SUMMARYThe clinical impact of antimicrobial resistance on the outcome of pneumococcal bacteraemia has remained unclear. This study aimed to evaluate risk factors for mortality and determine the impact of antimicrobial resistance on clinical outcomes. A total of 150 adult patients with pneumococcal bacteraemia were identified over a period of 11 years at Seoul National University Hospital. Of the 150 patients, 122 (81·3%) had penicillin-susceptible (Pen-S) strains and 28 (18·7%) penicillin-non-susceptible (Pen-NS) strains; 43 (28·7%) had erythromycin-susceptible (EM-S) strains and 107 (71·3%) erythromycin-non-susceptible (EM-NS) strains. On multivariate analysis, elevated APACHE II score [odds ratio (OR) 1·24, 95% confidence interval (CI) 1·14–1·34, P<0·001) and presence of solid organ tumour (OR 2·99, 95% CI 1·15–7·80, P=0·025) were independent risk factors for mortality. Neither erythromycin resistance nor penicillin resistance had a significant effect on clinical outcomes. However, for the 76 patients with pneumococcal pneumonia, the time required for defervescence was significantly longer in the EM-NS group than in the EM-S group (5·45±4·39 vs. 2·93±2·56, P=0·03 by log rank test). In conclusion, antimicrobial resistance does not have an effect on mortality in adult patients with pneumococcal bacteraemia.