Objective. To assess Peruvian mothers' knowledge and recognition of pneumonia in children under 5 years of age, the mothers' attitude toward seeking medical help if they had a child with signs of pneumonia, and their perception of a Government of Peru pneumonia campaign. Methods. In this cross-sectional study, 501 mothers were selected randomly from 20 low-income communities of the metropolitan area of Lima, Peru, and were interviewed between June and August 2000. Using SPSS software, descriptive statistics were applied to summarize the demographic data and the data regarding the mothers' knowledge of pneumonia and recognition of signs of the disease. Cross-tabulations and chi-squares were done to assess relationships between variables and to make comparisons. Results. About 84% of the mothers said that they knew what pneumonia is. Most believed that pneumonia is dangerous. A majority (58.7%) indicated that pneumonia is caused by lack of parental care. Only 28.9% believed that a virus causes the disease. More than 80% correctly picked rapid breathing and/or chest retraction from a list of possible signs and symptoms of pneumonia, and 94.6% said they were ready to take their child to the closest health center if they thought their child had pneumonia. Although 57.1% said they had heard about the Government of Peru pneumonia campaign, 69.3% of these mothers said they could not recall the motto of the campaign. Mothers who reported having heard of the campaign through TV were more likely than other mothers to correctly recognize the two major signs of pneumonia presented in the campaign. Conclusions. Although the percentage of mothers believing they can recognize pneumonia through rapid breathing and chest retraction seems to have increased in recent years, there is still a sizable percentage of mothers who remain uninformed about pneumonia and its possible fatal consequences. Efforts need to continue to educate Peruvian mothers about the causes, recognition of the signs, and treatment of pneumonia. The results suggest that the Government of Peru pneumonia campaign should use television much more, as well as the health centers, where most of the mothers receive medical attention and health information.