<jats:title>Abstract</jats:title><jats:p>New tricyclic sesquiterpenoids brasilamides A–D (<jats:bold>1</jats:bold>–<jats:bold>4</jats:bold>) and the known pinthunamide (<jats:bold>5</jats:bold>) have been isolated from cultures of the plant endophytic fungus <jats:italic>Paraconiothyrium brasiliense</jats:italic> Verkley. Their structures were elucidated primarily by NMR spectroscopy, and the structure of <jats:bold>1</jats:bold> was further confirmed by X‐ray crystallography. The absolute configuration of the C‐5 tertiary alcohol in <jats:bold>2</jats:bold> was assigned by analogy to <jats:bold>1</jats:bold> and confirmed by observing the circular dichroism of in situ generated [Rh<jats:sub>2</jats:sub>(OCOCF<jats:sub>3</jats:sub>)<jats:sub>4</jats:sub>] complex. Compounds <jats:bold>2</jats:bold>–<jats:bold>4</jats:bold> showed modest inhibitory effects on HIV‐1 replication in C8166 cells. Compounds <jats:bold>1</jats:bold> and <jats:bold>2</jats:bold> possess an unprecedented4‐oxatricyclo‐[3.3.1.0<jats:sup>2,7</jats:sup>]nonane skeleton.