A retrospective study was undertaken to determine the incidence of sinusitis as a source of fever in the intensive care unit (ICU) patient, evaluate the effectiveness of radiologic studies in diagnosing sinusitis, and develop guidelines that may help predict the result of antral lavage. Sixteen of 52 (30.7%) lavages in patients studied with plain films and 27 of 67 (40.3%) lavages in patients studied with computed tomography of the sinuses revealed purulence in the maxillary sinuses. Conversely, 23 of 30 (76.7%) of the cases with purulence in the middle meatus had purulence in the maxillary sinus (chi-squared = 27.1). If no purulence was seen, the results of the antral lavage were negative in 68 of 89 cases (76.4%). When physical examination was used in conjunction with computed tomography, 92.3% of lavages confirmed purulence in the maxillary sinus (chi-squared = 16.6). In conclusion, the most important factor in predicting a positive result with antral lavage is the presence of purulence in the middle meatus on physical examination in conjunction with the presence of sinus disease on computed tomography of the sinuses.