We evaluated direct and indirect greenhouse gas (methane (CH(4)) and nitrous oxide (N(2)O)) emissions from a vertical flow constructed wetland (CW) planted with forage rice. The gas fluxes from the CW surface water to the atmosphere (direct emission) and the dissolved gas concentrations in filtered water (indirect emission) from the CW were monitored. Direct and indirect emissions of CH(4)-C from the CW were lower than those reported in the literature. Direct fluxes of N(2)O-N exhibited positive (14 out of 41 sampling times) and negative (13 out of 41 sampling times) values, resulting in average N(2)O-N efflux from and influx to the CW of 17.7 +/- 18.8 and -18.9 +/- 15.2 mu g-N.m(-2).h(-1), respectively. N(2)O-N concentration in the filtered water ranged from 0.43 to 10.4 mu g-N . l(-1) and significantly correlated with NO(3)-N concentration in the soil pore water. Given these results, percentages of indirect emission to total (direct + indirect) emission during the experimental period were 2.9 and 86.7% for CH(4)-C and N(2)O-N, respectively. Emission factor (EF(5g)) of the indirect N(2)O-N emission was 0.00053-0.0086 kg N(2)O-N. (kg-N leaching/runoff) (1), comparable to those of indirect emission sources in the literature. These results indicate the importance of monitoring and controlling indirect N(2)O-N emission from a vertical flow constructed wetland.