Microscopic fungi are able to contaminate and deteriorate various food products and can subsequently cause health problems. Long usage of the same preservatives and disinfectants against spoilage fungi may lead to the development of fungal resistance to those chemicals. The objective of this study was to investigate the susceptibility of 3 Penicillium genus fungi, isolated from foodstuffs, to organic acid preservatives and some disinfectants, taking into consideration 2 aspects of their development: spore germination and mycelial growth. Susceptibility of Penicillium spinulosum, P. expansum and P. verruculosum to the preservatives, namely benzoic acid, sodium lactate, potassium sorbate, as well as disinfectants such as Topax DD, Suma Bac D10, Biowash and F210 Hygisept, was investigated. The biocides were used at concentrations of 0.1, 1.0 and 10%. Of the preservatives, benzoic acid and potassium sorbate showed the best inhibition, both on spore germination and mycelial growth. Benzoic acid at a concentration of a 0.1% reduced spore germination by 33-55%, and mycelial growth by 54-97%, whereas at 1% the inhibition was 74-85% and 97-100%, respectively. The effect of the disinfectants at a concentration of 0.1% on spore germination was 25-84% and on colonial growth 68-97%, while at 1.0% the reduction in spore germination reached 53-91% and the inhibition of growth 89-100%. In most cases, the same concentrations added to the media showed higher inhibitory effect on mycelial growth than on spore germination. It was noticed that the fungi responded rather unevenly towards the biocides, showing individual susceptibility.