Systemic fungal infections are increasing, and cause high morbidity and mortality. Treatment is challenging because fungi share many metabolic pathways with mammals. Current antifungals are losing effectiveness due to drug resistance. In immunocompromised patients Aspergillus fumigatus causes systemic aspergillosis, the most important disease due to inhalation of airborne spores. Mortality from aspergillosis exceeds 70% even with aggressive treatment. We need novel antifungal drug targets. Fungal cell wall components are promising targets for antifungal therapy as they are essential for fungi and absent from human. The sugar galactofuranose (Galf) is a 5-memberd ring form of galactose that is found in the cell walls of many fungi, but not in mammals. I used molecular biology and microscopy techniques to characterize Galf biosynthesis enzymes in the model species A. nidulans. I studied three enzymes that catalyze sequential steps in Galf biosynthesis: UgmA, UgtA and UgeA. UDP-galactopyranose mutase (UgmA) creates UDP-galactofuranose (UDP-Galf) from UDP galactopyranose (UDP-Galp) in the cytoplasm. The UDP-Galf transporter (UgtA) moves UDP Galf into membrane bound organelles for incorporation into cell walls. Upstream of UgmA, UDP-glucose/galactose epimerase (UgeA) converts UDP-glucose into UDP-Galp, the UgmA substrate. Neither UgmA nor UgtA has a human counterpart; UgeA is in the Leloir galactose metabolism pathway that found in many organisms including bacteria and humans. None of UgeA, UgmA and UgtA is essential for viability of A. nidulans, but deleting any one of them substantially reduces colony growth and sporulation. Wild type and Galf deletion strains (ugeA∆, ugmA∆ and ugtA∆) were quantified for colony growth, cell morphometry, spore formation and germination as well as wall architecture. Galf content was assessed by immunolocalization in wildtype and ugmA∆ strains, showing that ugmA∆ strain was completely depleted of Galf. Gene products were localized with fluorescent protein tags; both UgmA and UgeA were cytoplasmic, while UgtA was Golgi localized. The abundance of these proteins was regulated using the alcA promoter. Wall surfaces were imaged and force-probed using atomic force microscopy. Overall, Galf deletion strains had aberrant wall maturation, and poorly consolidated surfaces, indicating that Galf is necessary for full maturation of Aspergillus cell wall. Thus, Galf pathway appears to be promising as an antifungal drug development target. Galf deletion strains were assessed for sensitivity to antifungal agents in clinical use. They were significantly more sensitive to caspofungin and amphotericin B that target cell wall synthesis and cell membrane chemistry, respectively. Thus, anti-Galf drugs (once created) may be also useful in combination with existing drugs. In summary, both UgmA and UgtA are promising targets for antifungal drug development.