Field surveys were carried out between March to August 1998 to determine the drainage channel networks structure of Meurir stream, a first-order basin located in Marechal Cândido Rondon county, Paraná State, Brazil. The stream has a basin of 0.36 km2 and elevations vary from 350 to 410 m. The regional terrain is rolling to flat. The basin is predominantly rangeland and farms. The area is underlain by cretaceous tholeiitic basalts. The region has a subtropical climate with a average annual precipitation of about 1,200 mm. Channels length were mapped in the field with Brunton compass and sources locations were made bi-weekly onto the basemap. These records were employed to determine the extent of the channels types. The total length of drainage network in the study basin are 974 m. Perennial channels constitute 324 m (33.3 %), intermittent channels 349 m (35,8 %) and ephemeral channels 300 m (30,8 %). Field observations show that extent of channel flowing vary systematically with precipitation. For example, in August 23, heavy rainfall (60 mm) have caused rapid upstream migration of sources. After some hours, the length of channel flowing increases from 142 m (end point of perennial segment) to 428 m (end point of intermittent segment). The relationship between extent of stream flow and the discharge is very close. Stream discharge was monitored in the perennial segment and varied from 0.045 (July 25) to 19.530 l s-1 (August 23). This study have revealed a particular structure of channel system in humid environment and variations in the length of channel flowing in a short period.