Background and Purpose: Antifungal effects of a Bifunctionalized Allene with unprotected hydroxy group (3-Diphenylphosphinoyl-5-methylhepta-3,4-dien-2-ol) (BA-3) on pathogenic yeast and fungi had been established. BA-3 (50mg/ml, 25mg/ml, 12.5mg/ml, 6.25mg/ml and 3.125mg/ml) exerted different inhibitory effect on different yearst and fungi cells in vitro. The effects of BA-3 on eukaryotic cells have not been studied yet. The present study was aimed to assess the antifungal activity of BA-3 on pathogenic yeast and fungi. Experimental approach: In vitro antifungal test: Aspergillus niger, Penicillium claviforme, Saccharomyces cerevisae, Candida albicans 8673 and Candida glabrata 72 were treated for 24 hours with BA-3 (50mg/ml, 25mg/ml, 12.5mg/ml, 6.25mg/ml and 3.125mg/ml), Fluconazole (150 mg/ml) for yeast and Chlornitromycin (250 mg/ml) for fungi. The antifungal activity was assayed by the well diffusion method with digital caliper. Determination of minimum inhibitory concentrations(MICs): The MIC of BA-3, that shows antifungal activity, were determined by methods as described by  and MICs were read in μg/ml after over night incubation at 37oC. All experiments were made in replicate. Determination of Minimum fungal concentratio n(MFC):The MFC was carried out to check whether the test microbes were killed or only their growth was inhibited. Potato Dextrose Agar (PDA, Oxoid, Hampshire, UK) was prepared and sterilized at 121oC for 15 minutes, the medium was poured into sterile petri dishes and were allowed to cool and solidify. The contents of the MIC in the serial dilution were then subcultured on to the prepared medium, incubation was made at 37oC for 24 h, after which each plate was observed for colony growth. The lowest concentration of the BA-3 without a colony growth was recorded as the MFC. BA-3 had higher antifungal activity than tested antibiotic– Fluconazole for yeast and Chlornitromycin for fungi. Key Results: The results revealed variability in the inhibitory concentrations of BA-3 for given fungi and yeast. MIC of BA-3 at concentration 50 mg/ml for 24 hours notably inhibited growth of yeast C. glabrata72 and C. albicans. In contrast, MIC of BA-3 at concentration 25 mg/ml for 24 hours notably inhibited growth only of fungi A. niger. MFC of BA-3 at concentration 25 mg/ml for 24 hours notably inhibited growth of C. glabrata and C. albicans 8673. MFC of BA-3 at concentration 12.5 mg/ml for 24 hours notably inhibited growth only of fungi A. niger. For Fungi Imperfecta from P. claviformeand years S. cerevisae MFC it was not reported. Conclusions and Implications: Based on the results obtained we can conclude that the examined BA-3 has bactericidal activity towards both pathogenic yeast and Fungi Imperfecta, but in different concentrations.The BA-3 possesses biological activity, which is not well studied. We know only from literary data that they are used for inhibiting the biosynthesis of sterol from the pathogen responsible for Pneumocystis-cariniipneumonia (PCP) -a disease similar to AIDS. In our previous studies was shown that theBifunctionalized Allenes with protected hydroxy group (Dimethyl 3-methyl-1-[1-(tetrahydro-2H-pyran-2-yloxy)-ethyl]-hepta-1,2-dienephosphonate) (BA-1) and unprotected hydroxy group (Dimethyl 1-(1-hydroxyethyl)-3-methylpenta-1,2-dienephosphonate) (BA-2) exhibited antibacterial [8, 10] and antifungal activity [9, 11]. The results obtained show for the first time the existence of antifungal activity of BA-2 towards various pathogenic yeast and fungi.