Patients with end-stage renal disease (ESRD) and on dialysis are at increased risk of pneumococcal disease. We evaluated the immunogenicity of the 13-valent pneumococcal conjugate vaccine (PCV13) in this population. Eligible patients with ESRD and on dialysis were given a single dose of PCV13. The concentrations of serum antibodies against 13 pneumococcal capsular polysaccharides were measured at the baseline and at 2 and 12 months postvaccination. A response to the vaccine was defined as a >2-fold increase in antibody concentration from that at the baseline and an absolute postvaccination value of at least 1 g/ml. Seventeen patients completed the study. Increases in the concentrations of antibodies to the vaccine serotype were demonstrated 2 months after vaccination. The geometric mean antibody concentrations at 12 months postvaccination declined by 38% to 72% compared to those measured at 2 months postvaccination. A response to at least 1 serotype in the vaccine was seen in all patients at both 2 and 12 months postvaccination. The overall rate of the response to each individual vaccine serotype varied between 23.5% and 94.1% at 2 months postvaccination and 23.5% and 65% at 12 months postvaccination. Pain at the injection site was the most common local reaction. Vaccination with PCV13 induces antibody responses to vaccine serotypes in patients with ESRD and on dialysis at 2 months postvaccination. However, the decline in antibody concentrations at 12 months postvaccination with a conjugate pneumococcal vaccine requires further study. (This study has been registered at ClinicalTrials.gov under registration no. NCT01974817.) P atients with end-stage renal disease (ESRD) and on dialysis are predisposed to infections with Streptococcus pneumoniae (1). Mortality rates from pneumonia in dialysis patients are about 10 to 16 times higher than those in the general population (2, 3). Furthermore, the emergence of multiple-antibiotic-resistant pneumococcal strains has added to this therapeutic challenge. This has led to an increased focus on vaccination for the prevention of pneumococcal diseases in this subset of patients.End-stage renal disease is associated with disorders of the adaptive immune system, which result in decreases in antigenpresenting function, the T-cell-mediated immune response, and immunological memory (4, 5). These patients are thus at risk of vaccine hyporesponsiveness. There is evidence of a decreased immunologic response to the 23-valent pneumococcal polysaccharide vaccine (PPSV23) in patients undergoing dialysis compared to that in the general population (6, 7). Moreover, a rapid decline in anti-pneumococcal IgG levels is observed in patients with ESRD within 1 year after vaccination with PPSV23 (8).PPSV23 predominantly induces a T-cell-independent immune response, and hence, immunologic memory is not achieved (9, 10). Conjugate polysaccharide vaccines, which incorporate a protein carrier (diphtheria toxin cross-reactive material 197 [CRM 197 ]) to the purified capsular saccharides of S. pneumoni...