Five biologically active daphnane orthoesters have been isolated from Pimelea species (Thymelaeaceae). Four of these possessing antineoplastic activity against in vivo murine P-388 lymphocytic leukemia are gnidimacrin from P. ligustrina, simpleximacrin from P. simplex, linimacrin d and Pimelea factor P3 from P. linifolia. Linimacrin c from P. linifolia and the other four compounds showed piscicidal activity. Gnidimacrin and Pimelea factor P3 have previously been isolated from other members of the Thymelaeaceae. Simpleximacrin and linimacrins c and d are new compounds.