Abstract: A micro-catheter including an inner primary liner and a plurality of concatenated tubes is provided. The primary liner extends substantially from the proximal end to the distal end of the catheter. Each of the tubes has a respective inner surface that is fused to the outer surface of the primary liner. For each and every pair of tubes, the outer diameter of the more proximally located tube is equal to or greater than the outer diameter of the more distally located tube. Each of the tubes may have different physical properties and dimensions for making customized micro-catheter profiles.