Chemical investigations of the aerial parts of the Australian plant Eremophila microtheca resulted in the isolation of three new serrulatane diterpenoids, 3-acetoxy-7,8-dihydroxyserrulat-14-en-19-oic acid (1), 3,7,8-trihydroxyserrulat-14-en-19-oic acid (2), and 3,19-diacetoxy-8-hydroxyserrulat-14-ene (3) as well as the previously reported compounds verbascoside (4) and jaceosidin (5). Acetylation and methylation of the major serrulatane diterpenoid (2) afforded 3,8-diacetoxy-7-hydroxyserrulat-14-en-19-oic acid (6) and 3,7,8-trihydroxyserrulat-14-en-methyl-19-benzoate (7), respectively. The antibacterial activity of 1-7 was assessed against a panel of Gram-positive and Gram-negative bacterial isolates. All the serrulatane compounds exhibited moderate activity against Streptococcus pyogenes (ATCC 12344) with minimum inhibitory concentrations (MICs) ranging from 64-128 姯mL. Serrulatane 1 demonstrated activity against all Gram-positive bacterial strains (MICs 64-128 姯mL) except for Enterococcus faecalis and Enterococcus faecium. This is the first report of natural products from Eremophila microtheca.