Objective To study the factors relating to failure of vacuum assisted closure (VAC)therapy for pressure ulcers control in order to guide the clinical indications.Methods A retrospective cohort study of 75 patients with pressure ulcers to undergo VAC therapy was conducted.Correlations between 12 risk factors and VAC therapy failure were analyzed.The statistical prognostic factors were screened and the sensitivity,specificity,positive predictive value and negative predictive value of them were analyzed.Risk factors for VAC failure were determined by using Logistic regression analysis.Results Among the 75 patients,17 patients failed to respond to the VAC therapy.The failure rate of VAC therapy had correlations with positive blood cultures,bony exposure,hypoalbuminemia (alb ＜25 g/L) and wound depths≥ 4 cm (70.0％,50.0％,38.5％ and 40.9％,respectively),but the Logistic regression analysis found that the 4 factors were not the independent risk factors for failure of VAC therapy.Conclusions Pressure ulcer patients with positive blood cultures,bony exposure,hypoalbuminaemia (alb ＜25 g/L),and wound depth≥4 cm tend to have a higher failure rate in VAC therapy,which are the relative indications for VAC therapy.