A series of silyl, germyl and alkyl substituted trifluoroacetylfurans has been synthesized under Friedel-Crafts electrophilic acylation conditions. Biological investigations have demonstrated that germyl derivatives of trifluoroacetylfuran are more toxic than the silicon analogues. 5-Triethylgermyl-2- trifluoroacetylfuran was the most toxic compound (CD(nabla), 11.2 mg kg(-1), i.p. for white mice), 200 times more toxic than the silicon analogue. 5-t-Butyl- and 5-trimethylsilyl-2-trifluroacetylfuran prolong the duration of ethanol anaesthesia by 220 and 140%. 5-Triethylgermyl-2-trifluroacetylfuran exibited high anesthetic activity in hexobarbital test (prolonged the duration by 137%). Some of compounds influenced muscle tone and locomotor coordination parameters. 5-Triethylgermyl-2-trifluomacetylfuran exibited analgesic activity (D(nabla), 0.9 mg k}(-infinity)).