this study aimed to quantify the levels of protein and minerals in common bean lines from the germplasm bank of universidade federal de lavras and to investigate the relationship between color and the mineral and protein contents of the beans. one hundred common bean lines with carioca, black and other grain color patterns were assessed for the protein levels and the mineral contents of phosphorus, potassium, calcium, magnesium, copper, manganese, zinc, and iron. genetic variability was detected among the different groups and also between lines within each group. in general, the protein, iron and zinc contents were highest in the black bean lines. the carioca grain was outstanding for manganese and magnesium and the other grain colors for calcium. positive correlations between most nutrients were observed. this indicates the possibility of obtaining lines with higher nutritional value by selection.