A retractable dog leash system is designed to attach to the collar of a pet and be permanently worn in this manner is small and lightweight, and comprises an ergonomic handle that fits neatly against the case when the leash is in a retracted condition. Advantageously, the leash system comprises a leash retraction biasing mechanism that is free on one end permitting an unwinding of the biasing mechanism and not merely a tightening of it.