The author lists the most frequent bacterial agents isolated from the nose and pharynx samples of children that visited the Child Health Centre from 1983 to 1986. The gram-positive bacteria found most often were: Staphylococcus aureus (44% in 1983, 40% in 1986). Streptococcus pneumoniae (6% in 1983, 12% in 1986), and Streptococcus haemolyticus of group "A" (14% in 1983, 19% in 1986). The isolated gram-negative bacteria were: E. coli (14%), Klebsiella enterobacter (8%), and Proteus species and Pseudomonas aeruginosa (2 to 4% [4, 6, 7, 16]). According to the author's analyses Staphylococcus aureus is highly sensitive to cloxacilline (96%, no changes in the 4-year period), then to sulphametoxasol-trimetorpine (95%), to lincomycine (85% no change), while to penicilline it is entirely resistant. Streptococcus pneumoniae proved sensitive to ampiciline, lincocine and erythromycine (96%), to cephalosporines (83%) and to sulphamides (85%). Streptococcus haemolyticus from group "A" reacted to penicilline excellently. The greatest sensitivity to gram-negative bacteria E. coli related to aminoglycosides (97%), sulphonamides (96%), chloramphenicol (91%), and to cephalosporines (90%, in 1986 only 60%). Klebsiella enterobacter reacted to aminoglycosides (97%), sulphonamides (92%) and chloramphenicol (83%) and Pseudomonas to aminoglycosides (95%), gentamycin (92%), while to cephalosporines and ampicillin preparations it proved totally resistant.