Nine new polyprenylated acylphloroglucinol derivatives, hypercohins B-J (1-9), and nine known analogues were isolated from the aerial parts of Hypericum cohaerens. The structures of 1-9 were elucidated based on spectroscopic analysis, and the absolute configuration of 1 was confirmed by X-ray crystallographic analysis. The inhibitory activities of these isolates on acetylcholinesterase and five human tumor cell lines were tested, and hypercohins B-D (1-3) exhibited moderate inhibitory activity (IC₅₀ 5.8-17.9 μM) against the tested tumor cell lines.