The root canal walls of twenty -five deciduous molar teeth with exposed and necrotic pulps were examined using thescanning electronmicroscope. Immediately after extraction, all teeth were fixed in Kamosky's solution. The coronal portion of the tooth was sectioned at about 2mm above the enamel cemental junction.The mesial and distal roots were separat~d and either split in the mesio-distal or bucco-lingual direction. All specimens were prepared for SEM. Obsevations showed that all roots were infected with organisms consisting of cocciand short rods. Some of the coccihad penetrated the dentine layer. However, the distribution of organisms is. not uniform throughout thecanals. Bacterialinvasion ismostinthecoronal region and reduces towards the apical region: Accompanying bacterial invasion is root canal walls deterioration. The odontoblastic processes are the first to deteriorate followed by the predentine layer.