Pneumococcal (PC) vaccination is recommended for patients with chronic lymphocytic leukemia (CLL). However, response to vaccines has been investigated in a small series of CLL patients. We analyzed the antibody response and outcomes of 112 CLL patients who received the 13-valent pneumococcal conjugate vaccine (PCV13). An immune response was defined by a twofold increase in the PC-IgG levels assessed by ELISA. The median age of patients was 68 years, 23.2% showed IgG levels ≤ 400 mg/L, 6.3% progressive disease, 52% unmutated IGHV. Twenty-two (19.6%) patients were treatment-naïve and 90 (80.4%) previously treated (40.2% front-line chemoimmunotherapy; ibrutinib first/advanced-line, 9.8%/21.4%; idelalisib advanced-line, 8.9%). Nine (8%) patients developed an immune response, eight treatment-naive, and one on front-line ibrutinib. No responses were observed in patients previously treated with chemoimmunotherapy. Age ≥ 60 years (p = 0.007), IgG levels < 400 mg/L (p < 0.0001), prior treatment (p < 0.0001), and signs of disease progression (p = 0.04) were associated with a lower response rate. Pneumonia-free survival was significantly shorter in patients with clinical signs of progressive disease (HR, 8.39), prior pneumonia (HR, 7.03), and TP53 disruption (HR, 2.91). In conclusion, our results suggest that vaccination should be offered at diagnosis to CLL patients with early stage and stable disease who have better resources for an effective immune response.