October coffee exports totalled 38,926 60-kilo sacks, down from 44,878 sacks in October 2004, according to the institute's monthly exports report.
October is the first month of the 2005/06 coffee harvest season, which is seen suffering losses from heavy rains caused by recent storms in the region.
The coffee institute said last month that Costa Rica lost between 5-10 percent of its 2005/06 crop because of rains which knocked beans from plants and triggered outbreaks of the mycena fungus, which thrives in moist regions.