The present invention relates to an apparatus and method for loading radioactive brachytherapy seeds into a seed cartridge for use with an applicator. Embodiments of the apparatus according to the present invention may include a number of contact points of a size and shape designed to conform to the main body of a brachytherapy seed. The apparatus may hold the seeds until the seeds are placed within a channel of the seed cartridge, at which point the seeds may be released from the contact sites by the application of a force to the seeds or by some other mechanism. The apparatus may be made from a flexible material so that the seeds may be released by the application of a tension force. According to embodiments of the method of loading the seed cartridge, seeds in the loader may be positioned in relation to the body of the loading apparatus and the ends of the seeds may be aligned with the channel of the seed cartridge. A seed may be placed in the channel so that a gripping portion of the loading device protrudes from an access portion of the channel. The apparatus may include gripping features so that the loading apparatus can be held firmly during the loading process.