BACKGROUND: As chronic obstructive pulmonary disease (COPD) progresses, exacerbations can occur with increasing frequency. One goal of therapy in COPD is to try and prevent these exacerbations, thereby reducing disease morbidity and associated healthcare costs. Pneumococcal vaccinations are considered to be one strategy for reducing the risk of infective exacerbations. OBJECTIVES: To determine the safety and efficacy of pneumococcal vaccination in COPD. The primary outcome assessed was acute exacerbations. Secondary outcomes of interest included episodes of pneumonia, hospital admissions, adverse events related to treatment, disability, change in lung function, mortality, and cost effectiveness. SEARCH STRATEGY: We searched the Cochrane Airways Group COPD trials register using pre-specified terms. We also conducted additional handsearches of conference abstracts. The last round of searches were performed in April 2006. SELECTION CRITERIA: Only randomised controlled trials assessing the effects of injectable pneumococcal vaccine in people with COPD were included. DATA COLLECTION AND ANALYSIS: Two review authors independently extracted data and three review authors independently assessed trial quality. MAIN RESULTS: Although 10 studies cited in 11 publications were identified that met the inclusion criteria for this review, only four of these provided data on participants with COPD. The studies which did provide data for this review consisted of two trials using a 14-valent vaccine, and two using a 23-valent injectable vaccine. Data for the primary outcome, acute exacerbation of COPD, was available from only one of the four studies. The odds ratio of 1.43 (95% confidence interval (CI) 0.31 to 6.69) between interventions was not statistically significant. Of the secondary outcomes for which data were available and could be extracted, none reached statistical significance. Three studies provided dichotomous data for persons who developed pneumonia (OR 0.89, 95% CI 0.58 to 1.37, n = 748). Rates of hospital admissions and emergency department visits came from a single study. There was no significant reduction in the odds of all-cause mortality 1 to 48 months post-vaccination (Peto odds ratio 0.94, 95% CI 0.67 to 1.33, n = 888), or for death from cardiorespiratory causes (OR 1.07, 95% CI 0.69 to 1.66). AUTHORS' CONCLUSIONS: There is no evidence from randomised controlled trials that injectable pneumococcal vaccination in persons with COPD has a significant impact on morbidity or mortality. Further large randomised controlled trials would be needed to ascertain if the small benefits suggested by individual studies are real.