A 65-year-old man was admitted to our hospital with severe community-acquired pneumonia (CAP) caused by mucoid type Streptococcus pneumoniae, which was diagnosed by typical colony findings on agar medium. His condition deteriorated despite adequate and susceptible antibiotic therapy, therefore, azithromycin was added to his treatment, following which he began to show an improvement. We compared the clinical differences between mucoid and non-mucoid type pneumococcal CAP in our hospital and found the C-reactive protein titer and scores of infiltrative shadows to be significantly higher in mucoid than in non-mucoid group. Furthermore, the duration of required antimicrobial therapy was significantly longer in the mucoid group. These findings indicate that mucoid type pneumococcal CAP may present a more severe clinical picture and greater resistance to antimicrobial agents than non-mucoid pneumococcal CAP, therefore, it should be recognized as an important clinical phenotype.