Abstract: A Monocillium species isolated from a soil sample which grown optimally in Czapek`s dox broth (acidic) medium yielded the metabolic compound HB identified as a mixture of novel compounds, Monocillinols A and B. Antibacterial activities of the compound were observed against fifteen Gram positive and Gram negative pathogenic organisms. The compound showed significant antibacterial activities against all pathogenic organisms tested except Gram negative Shigella sonnei. The minimum inhibitory concentration (MIC) values of the compound were determined against Bacillus subtilis, Sarcina lutea, Staphylococcus aureus, Shigella dysenteriae, Escherichia coli and Salmonella typhi and found to be 128, 256, 128, 128, 128 and 128 g/ml, respectively.