The magnitude of non-sparing anaerobic (NSA) infections has been defined in the postoperative wounds on colorectum in children (57.1%), general surgery (0%), abdominoperineal and uterocervical operations (11-45%) in gynaecologic and obstetrical cases and perforative peritonitis (25.8-32.3%). Children below the 6 months age group bear less risk of acquiring NSA infection. Under certain situations, metronidazole combats NSA infections in a better way than other antibacterials. The bacteriology of NSA infections has been probed at the species level in the gynaecologic and obstetrical patients. The species of normal cervix (44.6%) are represented in wounds involving abdominal wall (11%), perineum (22.8%) and uterocervix (45.6%) to suggest endogenous infection. Out of the 22 species of NSA isolated, Peptostreptococcus anaerobius, Acidaminococcus fermentans and Peptococcus prevotii are the commonest. Others were Peptococcus niger, Gaffkya anaerobia, Lactobacillus bulgaricus, Actinomyces bovis, Bacteroides oralis, Fusobacterium gonidiaformans and the different species of peptococcus, peptostreptococcus, eubacterium, propionibacterium and fusobacterium. The weight of evidence indicated a pathogenic role of Peptostreptococcus anaerobius and Ruminococcus flavefaciens, in view of their heavy growth. The umbrella of antibacterials reduced Gram-positive anaerobic cocci from 40% to 16%. The facultative anaerobes Staph aureus, Staph epidermidis, Kl pneumoniae and proteus appeared as the exogenous agents of nosocomial infections.