The incidence of fungi inside certain historic buildings and premises used for storing heritage collections in Havana (Cuba) and fungal contamination of the items stored there have been assessed. Cultivable airborne fungi were sampled using the slit-to-agar impaction method with a type S Chirana aeroscope; various substrates were swab-sampled in addition. Most common were Aspergillus, Penicillium and Cladosporium. The physiological features of some of the fungal strains isolated from the substrates were examined in order to evaluate their potential for biodeterioration. Numerous Aspergillus strains were able to produce cellulase and acids and to hydrolyse gelatine, while Cladosporium displayed the greatest ability to produce polyphenol oxidases. One third of the strains tested, all belonging to the genera Aspergillus and Penicillium, produced pigments.