Purpureocillium is a genus recently proposed to accommodate Paecilomyces lilacinus, a well studied species that has biotechnological properties and an ability to cause human infections. Since contradictory data have been reported on the intraspecific genetic variability of P. lilacinum, we have carried out a polyphasic study of a set of clinical and environmental isolates of this species. Detailed morphological examination and sequence analysis of four different loci, including the ribosomal internal transcribed spacer, the domains D1 and D2 of the 28S rDNA, EF-1a and the largest subunit of RNA polymerase II (rpb1), showed that P. lilacinum formed a well supported phylogenetic clade with low intraspecific variability. The new species Purpureocillium lavendulum, which has vinaceous colonies similar to those of P. lilacinum, is proposed. It is characterized by the lack of growth at 35 C, the production of a yellow diffusible pigment and by subglobose or limoniform conidia.