Abstract OBJECTIVES Postoperative organ dysfunction is common after cardiac surgery, particularly when cardiopulmonary bypass (CPB) is used. The Sequential Organ Failure Assessment (SOFA) score is validated to predict morbidity and mortality in cardiac surgery. However, the impact of CPB duration on postoperative SOFA remains unclear. METHODS This is a retrospective study. Categorical values are presented as percentages. The comparison of SOFA groups utilized the Kruskal–Wallis chi-squared test, complemented by ad hoc Dunn’s test with Bonferroni correction. Multinomial logistics regressions were employed to evaluate the relationship between CPB time and SOFA. RESULTS A total of 1032 patients were included. CPB time was independently associated with higher postoperative SOFA scores at 24 h. CPB time was significantly higher in patients with SOFA 4–5 (**P = 0.0022) or higher (***P < 0.001) when compared to SOFA 0–1. The percentage of patients with no/mild dysfunction decreased with longer periods of CPB, down to 0% for CPB time >180min (50% of the patients with >180m in of CPB presented SOFA ≥ 10). The same trend is observed for each of the SOFA variables, with higher impact in the cardiovascular and renal systems. Severe dysfunction occurs especially >200 min of CPB (cardiovascular system >100 min; other systems mainly >200 min). CONCLUSIONS CPB time may predict the probability of postoperative SOFA categories. Patients with extended CPB durations exhibited higher SOFA scores (overall and for each variable) at 24 h, with higher proportion of moderate and severe dysfunction with increasing times of CPB.