Parasitic and fungal organisms which are likely to cause pulmonary infections in immunosuppressed patients can be detected in broncho-alveolar fluid (BAL fluid). Single and standard methods, such as direct examination of the pellet, eosine-methylene blue fast (RAL 555), cultures in usual mediums of mycology must be systematically applied to this sample and may help detect these organisms without further exploration. If the results are negative, more recent techniques can be used if they present a real asset: an easier reading and mostly an improved sensitivity. Such is the case of immuno-fluorescence assay with monoclonal antibodies for detection of Pneumocystis carinii, and inoculation of MRC5 fibroblast cell line in tissue culture for isolation of Toxoplasma. Fungal pulmonary infections diagnosis has not yet succeeded in benefiting from modern findings: latex tests proposed for the detection of circulating antigens are nor sensitive nor specific, except the "Crypto LA test". Considering the relatively frequent association with other infectious agents, the detection of a parasitic or fungal organism in the BAL fluid should not interrupt investigation of this sample; neither should it lead to hasty conclusions regarding the responsibility of this agent in acute pneumopathy. This role will have to be evaluated according to criteria which are different for each isolated organism.