The cell wall represents a specific target in the development of new antifungal agents. The biosynthesis of (1,3)β-d-glucan, a structural element of the fungal cell wall, constitutes a valuable model for morphogenetic studies. Schizosaccharomyces pombe contains four bgs (beta glucan synthesis) genes, whose encoded proteins share high sequence identity, and probably are the catalytic subunits of four different (1,3)β-d-glucan synthase (GS) activities. The bgs1⁺ mutants cps1-12, cps1-N12 and cps1-191 are altered in the septation process. However, different bgs4⁺ mutants present distinct phenotypes; cwg1-1 and cwg1-2 display a thermosensitive lethal phenotype, which is accompanied by a dramatic GS decrease; orb11-59 is defective in cell integrity; and pbr1-1, -2, -3, -6 and -8 are resistant to GS-specific antifungal drugs. We have performed a comparative functional analysis of the three Bgs proteins, Bgs1p, Bgs3p and Bgs4p, each one essential for the vegetative cycle. We have located the mutations responsible for the phenotypes of the bgs1⁺ and bgs4⁺ mutants. Next, we have made series of mutants with the mapped substitutions in the three Bgs proteins. We have also included four Echinocandin-resistance mutations of the Saccharomyces cerevisiae homolog proteins FKS1 and FKS2. The mutants have been tested for a series of phenotypes, such as resistance-hypersensitivity to GS-specific drugs, thermosensitivity, osmotic protection, morphology, etc. We show that although the analyzed amino acids are identical or well conserved in all the Bgs proteins, each mutation produces different phenotypes in each protein, conferring even lethality and no effect depending on the protein. The presented results will be discussed.