Trace gas fluxes of carbon dioxide, methane, nitrous oxide, and nitric oxide (CO2, CH4, N2O, and NO) from surface soil were measured manually in an undisturbed forest at the Tapajos National Forest Seca-Floresta Site, which is within the footprint of the km 67 eddy flux tower. Measurements were made in January 2000 through April 2004, approximately twice per month. On each sampling date, up to four sets of 30-m lines were established off the existing transects at the Seca-Floresta site. Along each line eight chambers were installed for gas collection. In addition soil samples were collected for analysis of soil moisture as water-filled pore space (WFPS). There is one comma-delimited ASCII file with this data set.