Abstract: The invention relates to a device and a method for loading hollow implantation needles with radiation sources made of radiation source chains, and a radiation source chain for interstitial brachytherapy of tissue. It is the object of the invention to develop a device and a method for packing and feeding of radiation sources made of radiation source chains as well as a radiation source chain for interstitial brachytherapy of tissue, whereby a precisely metered quantity of connected radiation sources (seeds) that has been predefined for implantation, and optionally of spacers, can be inserted without remnants into hollow needles located inside or all designed of tissue to be treated, by simple and reliable manipulation without manual intervention. The design safely guides the contiguous seeds through hollow needles with low-friction, reduces the risk of a malfunction and allows optimal cleaning and/or sterilization, while also reliably protecting the surroundings from radiation.