We have compared the profiles of toxigenic molds and their mycotoxins after collection of dust from work-place buildings by simple use of adhesive tape. After cultivation of the molds on a variety of agars, and selected molds in appropriate liquid media, mycelia, conidia, spores, and culture filtrates were collected, extracted with methanol, and the extracts were concentrated. The extracts were investigated by TLC on silica gel plates with chloroform-xylene-acetone, 6 + 3 + 1 ( v/v ), as mobile phase and, usually, UV detection. After theoretical simulation, and optimization of several systems, these conditions were selected because they furnished better separations and were highly reproducible, thus enabling comparison of results. The results obtained revealed it was possible to identify differences among species of toxigenic molds and most of the mycotoxins present in work places by use of TLC. Our results were indicative of differences among offices, student laboratories, instrumental laboratories, ster...