Twenty-one derivatives of 4-acyloxy-1-(1, 3-dioxolan-2-ylmethyl) piperidines (2) and their quaternary salts (6) were synthesized and tested for anticholinergic activities. The piperidine derivatives (2) exhibit moderate activities. Among the quaternary salts (6), the trans-isomers were always more active than the corresponding cis-isomers.