A series of novel thiophene derivatives 3-17 were synthesized by initial reactions of 2-amino-4,5,6,7-tetrahydro-N-phenylbenzo[b]thiophene-3-carboxamide 1 and 2-amino-4,5,6,7-tetrahydro-benzo[b]thiophene-3-carbonitrile 7 with different organic reagents. The structures of newly synthesized compounds were confirmed by IR, 1H NMR, MS spectral data and elemental analysis. Initially the acute toxicity of the compounds was assayed via the determination of their LD50. All the compounds were screened for their antiarrhythmic, serotonin antagonist and antianexiety activities and they showed high activity compared with procaine amide, lidocaine, diazepam and buspirone as positive controls. The detailed synthesis, spectroscopic data, LD50 and pharmacological activities of the synthesized compounds were reported.