The aim of the present study was to analyse the bacteriological factors during the process of dental alveolitis, relating it to a higher incidence of bacteraemia in adult rats subjected to neonatal malnutrition. We used forty male Wistar rats, suckled by mothers fed a diet during lactation containing 17 % protein in the nourished group (N) or 8 % protein in the undernourished group (UN). After weaning, the animals were given the Labina standard diet. After 90 d, these animals underwent upper right incisor extraction and induction of alveolitis. The oral microbiota was obtained using a swab and blood culture through venous blood. These procedures were performed before the extraction, 5 min after extraction, on the 21st day after alveolitis for groups N-21 and UN-21 and on the 28th day after alveolitis for groups N-28 and UN-28. Data were expressed as means and standard deviations for parametric data, and as medians and interquartile intervals for non-parametric data. Statistical significance was considered by assuming a critical level of 5 %. Before and after extraction, lower bacterial growth was observed per colony-forming unit (CFU) in the perialveolar region of the upper right incisors of undernourished animals, while the opposite was true after alveolitis, when a larger number of CFU was observed in these animals. The percentage of positive blood cultures obtained after alveolitis was greater in the undernourished animals. The present study thus demonstrated the influence of neonatal malnutrition in the perialveolar microbiota and in the development of bacteraemia after dental alveolitis.