The diagnostic interest of the search for soluble bacterial antigens, using counter-current immunoelectrophoresis (CIE) has been evaluated in 109 children hospitalized with acute infection. In meningitis, CIE was well correlated with cerebrospinal fluid (CSF) culture and allowed a rapid diagnostic orientation in 82% of meningitis which were confirmed by classical bacteriology (CIE has to be performed using CSF and concentrated urine). False positive results were observed with type B meningococcus, especially on urine samples. In respiratory infections, the search for soluble antigens was of no interest except for focal pneumonitis; in that case, CIE was more frequently positive (35%) than blood culture (28%) and led to a 31% increase of correct diagnosis (CIE must be performed using concentrated urine). Serum and pleural fluid investigations were less sensitive. CIE was not useful in case of upper respiratory or nonfocal broncho-pulmonary infection, due to its very low efficiency.