Deep sternal wound infection (DSWI) is a feared complication following cardiac surgery. This study describes clinical, microbiological, and treatment outcomes of DSWI and determines risk factors for complications. Of 55 patients with DSWI, 66% were male and mean age was 68.2 years. Initial sternotomy was for coronary artery bypass graft in 49% of patients. Sternal debridement at mean 25.4±18.3 days showed monomicrobial (94%), mainly Gram-positive infection. Secondary sternal wound infection (SSWI) occurred in 31% of patients, was mostly polymicrobial (71%), and was predominantly due to Gram-negative bacilli. Risk factors for SSWI were at least 1 revision surgery (odds ratio [OR] 4.8 [95% confidence interval {CI} 1.0-22.4], P=0.047), sternal closure by muscle flap (OR 4.6 [1.3-16.8], P=0.02), delayed sternal closure (mean 27 versus 14 days, P=0.03), and use of vacuum-assisted closure device (100% versus 58%, P=0.008). Hospital stay was significantly longer in patients with SSWI (69 days versus 48 days, P=0.04).