The type of fungi present on frescoes was investigated by sampling (adhesive tape; use of cotton swabs) from selected areas on two frescoes in the church of Ognissanti, Florence. The two 15th century frescoes investigated were Botticelli's St. Augustine and Ghirlandaio's St. Jerome. 23 different species were identified, 15 on the Botticelli where the majority of the colony forming units were Penicillium brevi-compactum Dierckx (61%) and P. Purpurogenenum Stolli (18%), and 13 on the Ghirlandaio, Aspergillus Versicolor Vuill. Tiraboschi being the most common (74%0, together with Cladosporium Sphaerospermum Penz. (22%). The materials most often used in fresco restoration, that is, calcium caseinate, masonite, animal glue were tested and found to be suitable substrates for species of Aspergillus and Penicillium, but not to Cladosporium cladosporides and C. Sphaerospermum. B/W photographs, disgrams, table, histogram, references.