SummaryAsthenomycoses represent more than 40 % of the opportunistic infections. An analysis of 1.250 published cases shows that these diseases are caused bij Candida (42.62),Aspergillus(23.28%), MucorandRhizopus(7.35%), Nocardia(5.44%), Cryptococcus(5.28%), Trichophyton(3.20%), Histoplasma(3.20%), Torulopsis(3.12%), Penicillium(1.44 %),Scopulariopsis(1.04%), Geotrichum(1.04%), Actinomyces(0.96•),Sporotrichum(0.80),Coccidioides(0.56%), Rhodotorula(0.40 %) andFusarium(0.24 %). Fungal associations are observed in 3 % of the cases. Mycological diagnosis is established by culture only in about 42 % of the cases, by histology only in 40 %, and by both methods in 18 %. Most frequently positive cultures are obtained from following specimens: blood, respiratory and cutaneous samples, ocular smears, urines, nails, spinal fluids, digestive specimens, and catheters. Positive histological diagnosis includes multiples biopsies, lung, digestive tract, nail, kidney, skin, brain and heart. Blood is mainly found positive forCandida, Torulopsis, and to a lesser extend forHistoplasma, respiratory system forCandida, AspergillusandNocardia; digestive tract forCandidaandGeotrichum; urine forCandida; spinal fluid forCryptococcus; eye forAspergillus, Penicillium, NocardiaandSporotrichum; skin forTrichophytonandCandida; nails forScopulariopsis; cervicofacial region forActinomyces; and catheters forCandida.Clinical features of asthenomycoses are extensive and deep Iesions., acute and widespread infection, atypical symptomatology, unsuccessful treatment if lately instored, unfavorable prognosis. Asthenomycoses are generally very severe. Dissemination frequency is 54 % and case fatality 67 %; withCandidait reaches 90 %. Predisposing factors include some primary diseases as well as their specific therapy. Hence, asthenomycoses caused byCandida, Aspergillus, NocardiaandCryptococcusdevelop in cancer patients or those having undergone traumatisms or surgery, especially organ transplantation (immunodepression); similarly, phycomycoses due toMucororRhizopusdevelop in patients with underlying diabetes mellitus or malignant haemopathy with neutropenia, or in severely burned. Experimental infections show the role of steroids, alloxan used as diabetogenic and certain antibiotics in the development of asthenomycoses.