In this paper, analysis and design of an underactuated compliant variable stroke mechanism are presented by employing its pseudo-rigid-body model (PRBM). During the design two cases are considered: prescribed output loading and constant input torque. It is shown that this mechanism is suitable where variable stroke is required corresponding to variable output loading. It is also observed that this mechanism is capable of providing nearly constant force over a wide range of input. The analysis and design approaches introduced in this study are also applicable for other similar underactuated compliant mechanisms. (C) 2010 Elsevier Ltd. All rights reserved.