Etiologic clues and prognostic indicators of community-acquired pneumonia (CAP) were sought in a 30-month study of under-5 admissions for acute lower respiratory infections (ALRIs). Investigative tools included blood culture, hemogram, immunofluorescence and serology. Associations of variables were tested using standard statistical tools. Of 419 ALRI, 323 (77%) had pneumonia, 234 (72.4%) bronchopneumonia, 66 (20.4%) lobar pneumonia and 23 (7.1%) both. More than 70% had poor parental socioeconomic parameters, 56.8% were overtly malnourished, 37.8% lived in overcrowded homes and 16.7% had been potentially exposed to wood smoke. Despite preconsultation antimicrobial use in 35.6%, 59 (28.8%) of 205 blood cultures proved positive; Staphylococcus aureus accounted for 22 (37.3%), Klebsiella species nine (15.3%) and Streptococcus pneumoniae three (5.1%). Ninety-two viruses were identified in 61 (50%) of 122 analyses. Respiratory syncytial virus (RSV) accounted for 28 (30.4%), parainfluenza virus type 3 (PIV-3) for 18 (19.5%) and influenza type-A (flu-A) 16 (17.3%). Twenty (16.4%) had > or = 2 viruses, while 40% of bacteremic cases with positive viral identification(s) had PIV-3. Pathogen detection was neither associated with hematologic parameters nor the final respiratory diagnosis. There were 35 (10.8%) deaths. Mortality was associated with maternal illiteracy (p = 0.045), wood smoke exposure (p = 0.006), preconsultation antimicrobial use (p = 0.04), malnutrition (p = 0.0003), bacteremia (p = 0.006) and polymorphonuclear leucocytosis (p = 0.023/0.013). RSV, PIV-3, flu-A, S. aureus and Klebsiella species constitute the major pathogens of pediatric CAP in urban Nigeria, while malnutrition, wood smoke exposure and bacteremia are strong risk factors of mortality. The poor prognostic import of antimicrobial abuse, vis-a-vis the apparent selection of necrotizing pathogens, are compelling indications for a reappraisal of current regional antimicrobial policies and exploring newer frontiers of disease control, including vaccine prevention.