Macroblood (MaHC) and microblood (MiHC) cultures were made in 200 neonates with a suspected diagnosis of septicemia so as to compare the efficiency of MiHC to isolate bacterias taking MaHC as reference. Blood was obtained by heel punctures in sterile test tubes soaked with polyanetol sodium sulphonate and later cultured in trypticase soy broth with sacharose 15 per cent. Positive percentage was 14.5 for MiHC and 12.3 for MaHC. MiHC reliability, taking MaHC as reference was 59 per cent. Only 29.7 per cent isolations were obtained with MiHC that increased to 40.2 per cent with MaHC technique. Culture efficiency was higher for Klebsiella, P. Mirabilis and S. paratiphy B using MaHC while for Staph. aureus MiHC proved to be a better technique. The use of polyanetol sodium sulphate instead of heparin, sachorose addition to the culture medium, larger samples and typical features of infection in neonates studied, account for findings and differences observed in a previous work.