Houseplants are being grown to increase the aesthetic value of indoor space but also to elevate air quality. Their infections with phytopathogens, however, not only have an impact on the plant physiology and appearance but also may lead to air contamination and, in consequence, affect human health. Present research is a case study of Echinopsis oxygona, known as the Easter Lily cactus, infected with a fungal pathogen. The phenotypic and molecular studies were conducted to identify the etiological agent of the lesions. Colony appearance and growth on various media, as well as the presence of fungal propagation structures were evaluated. Internal transcribed spacer (ITS) sequences from the isolated cultures were obtained, and the BLAST analysis was performed to estimate genetic similarity. The phenotypic and molecular tests allowed to identify the pathogen as Fusarium oxysporum and, to our knowledge, it is the first report on E. oxygona (as a pot plant) infected with this species in Poland. This fungus is a soil-born species and a well-known toxin producer. Therefore, it does not only reduce aesthetic value of the infected plant but also may lead to air contamination with mycotoxins and fungal structures.