Methods have been discovered that make it possible to continuously extrude tubes of P4HB and copolymers thereof. These methods allow tubes of P4HB and copolymers thereof to be produced without radial deformation of the tubes despite the slow crystallization of the polymer and copolymers. The methods can produce tubes of P4HB and copolymers thereof with tightly defined outside and inside diameters which are required for medical application. These tubes are produced by radial expansion at temperatures above the melting temperature of P4HB and copolymers thereof, and using low tube cooling temperatures and prolonged cooling times. The tubes made from P4HB and copolymers thereof are flexible, and can be prepared with high elongation to break values.
