The post-cardiac injury syndrome (PCIS) is an important cardiologic problem associated with heart surgery. The pathogenesis of the PCIS is poorly understood, but immunologic mechanisms are considered to be the most important. Accordingly, we investigated the profiles of pro- and anti-inflammatory cytokines [interleukin (IL) 8, IL-1β, IL-6, IL-10, tumor necrosis factor a (TNF-α) and IL-12p70], before and after the heart surgery in patients with or without the PCIS, and in the healthy controls. The surgery caused significant increase of all the aforementioned cytokines; in addition, the pre-operative values were significantly higher than in control patients. Moreover, when the relative changes of the IL-8 concentration (e.g. ratios between the concentration after the surgery to the concentration before the surgery) were compared between PCIS-positive and PCIS-negative patients (PCIS-positive: mean ration 1.7 ±0.64 vs. PCIS-negative: 1.0 ±0.11) the difference between the indexes was statistically significant (p < 0.001). This is a novel finding suggesting that changes in the serum IL-8 concentration after the heart surgery may predict the occurrence of the PCIS.