Objective: Infectious complications are the most common cause of unsatisfactory results of surgical treatment and prolongation of hospitalization in patients following spinal surgery. The purpose - to assess the microbiological characteristics of SSI in patients after posterior lumbar fusion for degenerative disease, and to determine the relationship between these characteristics and surgical features of SSIs. Methods: A single-center retrospective non-randomized cohort study was performed, 1563 patients aged 37 to 59 years were included in the study. Microbiological characteristics were analyzed, and their interrelations with the surgical features of all cases of SSIs were determined. Results: The incidence of SSIs was 2.67% (41). Monomicrobial SSIs were detected in 46.3% (19) patients, polymicrobial in 36.5% (15) cases, and negative results of inoculation in 17.07% (7) patients. The most frequent pathogens of SSIs in the study group were S. aureus and S. epidermidis - 37.9% (33) and 24.1% (21), respectively. The period of development of symptoms of SSIs in patients after posterior lumbar fusion averaged 25.9±65.3 days. Methicillin-resistant S. aureus and S. epidermidis (MRSA and MRSE) were verified in 24.1% (21) cases. Conclusions: Assessment of microbiological characteristics should be carried out in all diagnosed cases of SSIs in patients after spine surgical interventions, as these are closely linked to the surgical features of the infectious process. Also, the treatment tactics for this group of patients should be determined by a medical team working in conjunction. © 2018 Oficial da Sociedade Brasileira de Coluna. All rights reserved.