Aspergillus fumigatus is one of the most common inhabitants of the air-borne fungal flora and becoming increasingly important as a causative agent of life-threatening infections in immunocompromised hosts accounting for more than 90% of human Aspergillus infection [1,2,3]. In nature, A. fumigatus survives as saprophyte and propagates by highly dispersed conidia that are continuously inhaled by humans. In immunocompetent hosts, conidia are eliminated by the innate immune response, however when they overcome the immune defense mechanisms in the lung they germinate and invade the lung tissue. Different groups have been investigated the factors associated with pathogenicity of A. fumigatus. Several studies indicated that pigments such as melanin and derivatives are important factors of virulence in the pathogenesis of several important human pathogenic fungi. In the present study we analysed the ultrastructure and the melanin production in A. fumigatus conidia grown in different culture media. A clinical isolated of A.fumigatus was cultivated in Czapek, Sabouraud (SAB), Peptone Water and Yeast Extract-Dextrose (YED) media for 7 days at room temperature. Scanning and transmission microscopy techniques were used to analyse conidia ultrastructure and melanin production was evaluated by flow citometry and fluorescence microscopy. Our results suggest that distinct culture media induces changes on conidial morphology and modulate the melanin expression on the surface of A. fumigatus conidia.