The present study was carried out from 1994 to 1997 with the aim of testing the adaptation and seed yield of the new bean cultivar “Negro Medellín” in the humid tropical region of Southeast Mexico. Five trials were conducted in the state Veracruz , four in Chiapas and one in Guerrero. Trials were conducted according to available facilities at each site under residual moisture or rainfall conditions. Trials included 16 bean genotypes that were distributed in the field using a Complete Random Design with three replicates. Negro Medellín resulted outstanding in average yield, yield stability and wide adaptation, although it showed a better response in favorable environments (1226 kg/ha, bi >1 and S2d = 0). During the conduction of the trials, Negro Medellín was tolerant to widespread diseases: bean golden mosaic virus (BGMV), angular leaf spot (Phaoisariopsis griseola) and rust (Uromyces appendiculatus var. appendiculatus). However, in a location in the state of Veracruz, Negro Medellín was severely attacked by anthacnose (Colletotrichum lindemuthianum). In addition, Negro Medellín was evaluated in commercial plots in farmer’s fields at 10 locations in the humid tropics of southeast Mexico. In those plots Negro Medellín was compared to a set of different checks that included bred cultivars and landraces. Negro Medellín outyielded all checks by 10 to 25% and its average yield was 1300 kg/ha. Negro Medellín is in the process of being registered as a new bred bean cultivar for the lowland humid tropics of southeast Mexico.