The role of spinal instrumentation in the presence of infection is still controversial. Radical debridements of infected vertebrae and disc material and bone grafting usually leaves the spine unstable without some surgical stabilisation. We reviewed 31 cases of primary pyogenic spinal infection treated by radical debridement, bone grafting and posterior (30) or anterior (1) spinal instrumentation. The indication for surgery was the failure of conservative treatment (8), progressive neurological deficit (19) or the lack of diagnosis (3). The clinical, laboratory and radiological parameters were assessed pre and postoperatively. The mean period of follow-up was 3.8 years (1-12 years). The neurological deficit was progressive in 19 patients, following surgery all these patients were improved. The neurological deficit was established in one patient; following surgery, his neurological deficit did not improve. The infection was eradicated in all our patients. The following complications were encountered: (1) three patients developed deep wound infection, which responded to repeated debridement; (2) one death resulted from nosocomial septicaemia, (3) reoperation was carried out on one patient for implant failure and on another for a dislodged anterior bone graft. We conclude that spinal instrumentation may be indicated when after radical debridement of infected vertebrae and disc material and bone grafting the stability of the spine is still compromised. According to the location of the infection and the availability of suitable implants, anterior or posterior instrumentation may be necessary. With appropriate antimicrobial agents, the outcome has been satisfactory in our patients.