PURPOSE: To review available clinical trials of selective digestive decontamination (SDD) in patients requiring intensive care. DATA SOURCES: All relevant English-language articles from 1982 through 1992 were identified through MEDLINE search and article bibliographies. STUDY SELECTION: Twenty-one articles were identified; 16 articles were selected for analysis based on inclusion and exclusion criteria. DATA EXTRACTION: Occurrence rates for mortality, acquired pneumonia, and acquired tracheobronchitis were extracted for patients treated with SDD and for control patients. Cumulative risk differences were calculated for each of these outcomes. RESULTS: There was no significant difference between cumulative mortality rates for control patients (0.262; n = 1,165) and patients receiving SDD (0.243; n = 1,105) (p = 0.291; beta error rate = 0.16). The acquired pneumonia greater than that in patients receiving SDD (0.074; n = 1,031) (p < 0.0001). The acquired tracheobronchitis rate in control patients (0.117; n = 549) was also significantly greater than that in patients receiving SDD (0.065; n = 494) (p = 0.004). The rate of acquired pneumonia due to Gram-positive bacteria was similar between the control patients (0.033; n = 660) and the SDD-treated patients (0.033; n = 646) (p = 0.933). Colonization with pathogenic Gram-positive bacteria and pneumonia due to antibiotic-resistant Gram-positive bacteria appeared to occur more frequently in SDD-treated patients. CONCLUSIONS: These results suggest that SDD decreases the overall incidence of acquired pneumonia and tracheobronchitis in patients requiring intensive care. SDD had no apparent effect on the hospital mortality rate. The routine use of SDD cannot be supported by this meta-analysis. SDD may be useful in specific circumstances where a particular ICU or ICU population is found to have an excessive incidence of acquired infections. Any use of SDD should include careful patient surveillance for the emergence of infection due to bacteria not covered by the prophylaxis regimen and due to antibiotic-resistant bacteria.