||In 1999 maize germplasm bank took a research initiative of prebreeding in addition to the bank management, germplasm regeneration and introduction, and germplasm evaluation and core subset development. Dr. Salvador Castellanos joined the program for characterizing and advancing the cycle of selection of the tropical and subtropical pools. He has helped the work of prebreeding by August 1999. In this report baseline characterization of the tropical and subtropical gene pools are summarized for the future work in which further development and improvement of the gene pools are expected. Flint and dent pools are heterotic partners as they are bred to maximize combining ability between them, using the proper tester lines in the recurrent selection scheme. New sources of genetic variations will be added to the gene pools according to the heterotic pattern. The same heterotic pattern is maintained in the phase of recombination and introgression. Core subset accessions that have not been added in the pools are evaluated as potential donors to the gene pools. The Caribbean core subset was first evaluated for the heterotic patterns. Several of the accessions are passed onto the next phase of the breeding scheme. The goal is to use the bank accessions in prebreeding initiative. The study of the ex-situ bank management cost by IFPRI (International Food Policy Research Institute) as a SGRP project is the first of its kind to estimate real cost of managing the seed collection per accession per year and in perpetuity. Preserving maize and wheat collection in one seed facility is cost efficient. Current and future implication on the cost of the bank management and seed preservation is shown in the study. Regeneration cost of maize is much higher than that of wheat. However, the amount of management and preservation cost of each crop genetic resources is similar in the case of CIMMYT. SCA Latin American maize regeneration project has continued. We reported the summary of the project as of 1999. The project significantly added the new introductions to the maize collection from Latin America. Core subset analysis on LAMP was published in CD-ROM last year. We worked on introduction of the core subset accessions of LAMP into CIMMYT collection. Brazilian Dent maize accessions were evaluated to designate the core subset. The results were presented in the workshop in Brazil in November 1999. More evaluations on the race Celaya, Caribbean accessions, collection from Mixteca region of northern Oaxaca, and Collection of Chihuahua have been made for core subset development. As usual seed distribution from the bank is full-filled for more than 80 requests. The accession information from introduction, regeneration, collecting, evaluation, core subset, and seed distribution is being captured on continuous bases into the bank management system. A little advance has been made in upgrading the system due to lack of the programmer time during the year. Bar-code implementation and Bank management system migration to NT database areexpected in the next year.