SUMMARY.This paper presents the results so far obtained in an investigation, which has been carried on since 1915, into “spotting” in apples. The symptoms of “spotting” as they are found and develop in numerous varieties of apple are described. Several fungi have been isolated from spots and cultured in various artificial media with the production of spores.They include a new genus of Phomatales (Polyopeus) and nine new species, of which at least one,Pleospora pomorum, as the result of experimental inoculations, has been proved capable of parasitising apples. The fungi do not include any of the species hitherto reported as causal organisms in the United States, the only centre where investigations into the “spotting” of apples, as distinct from the “bitter pit” problem, has been undertaken.The work was commenced at the Wisley Gardens of the Royal Horticultural Society. During the building of the Society's laboratory it was continued, by the kindness of Professor V. H. Blackman, in the Department of Plant Physiology and Pathology at the Imperial College of Science and Technology. In was later carried on again at Wisley; the work however has been completed at the Imperial College.The authors' thanks are due to Professor Blackman for his kind help and criticism during th