Abstract The bacterial genus Thiobacillus is known for its ability to degrade concrete. A fungus was isolated from concrete samples and identified as a Fusarium species. Our data indicate that fungi also play an important role in the deterioration of concrete. We observed both weight loss and release of calcium when concrete was exposed to our isolate. Fungal degradation proceeded more rapidly than Thiobacillus-mediated degradation. Our study suggests that interaction between fungal metabolites and calcium in the concrete results in the formation of soluble calcium organic complexes.