A hemostasis valve has a housing having proximal and distal ends defining proximal and distal openings configured for passage of a medical device therethrough. The housing further defines a cavity between the proximal and distal ends. One or more rollers are received within the cavity and define end sections and a central section having a smaller diameter than the end sections. Sleeves are disposed about the rollers and are elastically deformable to form a fluid seal around the device. The sleeves each assume a first form when the device is absent from the cavity wherein a radially inner surface of the sleeve is located at a first distance from the central section of a roller and a second form when the device is present in the cavity wherein the surface is located at a second distance, less than the first distance, from the central section of the roller.