Hyaline, one-septate ascospores (HIS) are known in high concentrations in the air, and have been reported as Didymella exitialis . HIS ascospores were isolated from the air, photographed and cultured. The cultures grew into six taxa in Ascochyta , the Ascochyta state of D. exitialis , an undescribed taxon close to D. exitialis , the Ascochyta states of D. phleina, A. hordei, A. hordei var. europea and A. leptospora . It is concluded that the majority of airborne HIS ascospores belong to various species of Didymella , some as yet undescribed. The late colouration and roughening of ascospores and conidia is discussed, as is the role of Didymella ascospores in inhalant allergy.