The present study was designed to assess the effectiveness of Papaverine and Theophylline for the enhancement of tissue expansion. Twentyfour guinea pigs were evenly assigned to three groups. One group served as control, the other two were experimental. In one group, Papaverine was used for enhancement of tissue expansion, in the other, Theophylline. It was assumed that by using anticontractile agents, formation of the fibrous capsule around the expander could be inhibited, thus enhancing tissue expansion. The study revealed that the rate of expansion was significantly increased with the use of either agent, but it appears that there is no significant difference in the effectiveness of the two agents.