A series of 15 analogues of fendiline, and 34 derivatives of N-(3-phenylpropyl)-1-arylethylamine have been prepared for evaluation as positive allosteric modulators of GABAB receptors. The most active (EC50, 10 nM) was N-(3,3-diphenylpropyl)-1-(3-chloro-4-methoxyphenyl)ethylamine 6g.