Six previously undescribed ophiobolin-type sesterterpenes, namely, bipolatoxins A-F (1-6); and one previously undescribed pimarane-type diterpene, namely, 1 beta-hydroxy momilactone A (7); together with three known compounds, namely, 25-hydroxyophiobolin I (8), ophiobolin I (9), and ophiobolin A lactone (10); were isolated and identified from the endophytic fungusBipolarisspecies TJ403-B1. Their structures with absolute configurations were elucidated on the basis of extensive spectroscopic analyses (including 1D and 2D nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectroscopy data), single-crystal X-ray diffraction analyses, and comparison of experimental circular dichroism data. All compounds (except for5) were evaluated for antimicrobial potential, which indicated that bipolatoxin D (4) showed significant inhibitory activity againstEnterococcus faecaliswith a minimum inhibitory concentration (MIC) value of 8 mu g/mL, and ophiobolin A lactone (10) showed significant inhibitory activity againstAcinetobacter baumanniiandE. faecaliswith MIC values of 8 and 8 mu g/mL, respectively.