Eight grass pea lines grown in three different seasons were evaluated for the stability of seed yield, 100-seeds weight, flowering time, plant height and biomass. Significant differences existed among years, lines and lines x years interaction for all traits except for 100-seeds weight. Two methods of multivariate analysis cluster and principal components were utilized to determine: firstly, whether a pattern existed among lines in their response across years and secondly to examine the relationships among them. In both analysis each lines was presented as a vector whose elements were given by the performance of lines in each year. The analyses used arranged the lines into groups that where differentiable in terms of performances and stability.