The study examined 48 children aged 3 to 16 years presenting with clinical and radiological evidence of pneumonia, together with 12 age matched healthy controls. Based on radiological appearance, cases were classified into those with diffuse infiltrates and suggestive of viral or mycoplasma pneumonia and those with lobar or segmental infiltrates and suggestive of bacterial pneumonia. Both groups showed significant differences in relation to age and acute phase reactants i.e. CRP, ESR, WBC and PNL. Lobar pneumonia was commoner in late childhood (54.5%) and was characterized by significant elevation in CRP, ESR, WBC and PNL (P<0.05). Diffuse or patchy bronchopneumonia was commoner in early childhood (80.8%) and the CRP, ESR, WBC, and PNL elevations were significantly less than in lobar pneumonia. Acute phase reactants were more specific than radiological data in differentiating viral from bacterial pneumonia as they were independent of age. CRP was the single test with highest sensitivity (86.4%) and specificity (73.1%) compared to ESR, WBC and PNL. An apparent limit of 60mg/L was defined to be the borderline between viral and bacterial pneumonias in communities living in challenging circumstances.