Fluorescence microprobe analysis of painting layers permits the identification of organic binding media and varnishes in painting materials and makes possible spectrometric analysis of the fluorescent radiation emitted even in areas of very small linear dimensions. Analyses were carried out on a few samples from paintings by piero della francesca, filippino lippi, antonio and piero del pollaiolo and titian. The results seem worthy of further investigation. Diagrams, graphs. References, p.241.