Alzheimer's disease, characterized by deposits of amyloid β-peptide (Aβ), is the most common neurodegenerative disease, but it still lacks a specific treatment. We have discovered five chemically unrelated inhibitors of the in vitro aggregation of the Aβ17-40 peptide by screening two commercial chemical libraries. Four of them (1-4) exhibit relatively low MCCs toward HeLa cells (17-184 μM). The usefulness of compounds 1-4 to inhibit the in vivo aggregation of Aβ1-42 has been demonstrated using two fungi models, Saccharomyces cerevisiae and Podospora anserina, previously transformed to express Aβ1-42. Estimated IC(50)s are around 1-2 μM. Interestingly, addition of any of the four compounds to sonicated preformed P. anserina aggregates completely inhibited the appearance of SDS-resistant oligomers. This combination of HTP in vitro screening with validation in fungi models provides an efficient way to identify novel inhibitory compounds of Aβ1-42 aggregation for subsequent testing in animal models.