summaryNail infections caused byCandidaspecies are normally associated with chronic paronychia or chronic mucocutaneous candidiasis (CMCC). However, the role ofCandidain the pathogenesis of other primary nail dystrophies has been questioned in view of their response to antifungal therapy alone. In the present study of 86 patients with primary nail dystrophies from whichCandidawas isolated, three patterns of nail involvement were found. Nineteen patients, of whom 17 had CMCC, had total dystrophic onychomycosis of at least two nails. The second group consisted of 27 patients with paronychia and lateral onycholysis. In a further 40 patients, who did not have paronychia,Candidawas isolated from nails showing primary distal and lateral onycholysis. These changes were mainly seen in patients with peripheral vascular disease, particularly Raynaud's disease, or Cushing's syndrome. Nail biopsies from patients in the latter two groups confirmed the presence of yeasts and mycelium in the nail plate and 17 (46%) of those receiving antifungal therapy with ketoconazole or itraconazole showed complete clearance of the nail dystrophy. Good responses to therapy were seen more frequently in patients with peripheral vascular disease or Cushing's syndrome of whom 15 (72%) recovered; distal erosion of the nail plate, mycelium in the nail plate on biopsy or direct microscopy together with the isolation ofC. albicanswere all associated with good responses to antifungals. In addition to patients with CMCC or paronychia, therefore,Candidaappears to be a significant pathogen in some patients with primary onycholysis of the finger nails, particularly where there is underlying peripheral vascular disease or Cushing's syndrome.