Background: Allelopathy is considered as an effective and environmentally friendly method to control the weeds and consequently enhances crop production. Lantana camara L. is a major exotic weed spreading rapidly in wastelands and agricultural fields. The ability of this weed to germinate fast and to inhibit the growth of other neighboring plants smoothest way for its quicker growth in an ecosystem. Methods: This study was carried out at Bule Hora University in the biology laboratory to assess haricot bean (Phaseolus vulgaris L.) genotypes at germination stage under the effects of allelochemical leaf extract from Lantana camara L. at different concentration levels. L. camara leaf and seven genotypes of haricot bean responsible for this study were collected from the local farmer's farm land in Bule Hora Woreda with their local name. Experiment was carried out with completely randomized block design with three replications in petridishes where three seeds of haricot bean were planted in each 84 petridishes and 0 gram/100 millileter (control), 2 gram/75 millileter (treatment 1), 2 gram/50 millileter (treatment 2) and 2 gram/25 millileter (treatment 3) grinded powder of L. camara L.: distil water were applied to petridishes daily. Germination parameters like germination day, number of germinated seeds, plumule length, radicle length, shoot fresh weight, root fresh weight, shoot dry weight, root dry weight, germination percentage, germination index and inhibition or stimulation were collected. Results: The result showed that there were variation responses of haricot bean genotypes parameters to each concentration levels of L. camara leaf extracts. Germination day, plumule length and radicle length were significantly influenced by L. camara leaf extract. The values of germination day, plumule length, shoot fresh weight and root fresh weight were decreased with the increasing of concentration levels. From the all genotypes Nasir was highly influenced in days to germination which shifted from 7.67 to 10.33 days. The correlation between concentration and all parameters were also seen that concentration and parameters plumule length (-0.428), shoot fresh weight (-0.015), root fresh weight (-0.237), shoot dry weight (-0.074) and root dry weight (-0.144) showed negatively correlated with concentration level. It can be concluded that allelopathic leaf extracts of lantana can inhibit germination parameters of some haricot bean genotypes which should take attention by breeders and farmers to avoid such weed from the crops. Conclusions: Generally it can be concluded that concentrated aqueous leaf extract of L. camara L. weed species inhibited germination day, plumule length, shoot fresh weight and germination index of haricot bean (p. vulgaris L). High concentration levels of this chemical has high influential power on the germination parameters of this crop.