Principal component analysis has elucidated relationships between the concentrations of N, P, K, Mg, Ca, S, Na, Cu, Zn, Se, Mn and Fe in perennial ryegrass from pasture. Elemental concentration data from two independent collections of samples were used for the analyses; one collection consisted of plant tops, the other consisted of leaf material and inflorescences. The analysis has revealed that elements act in groups. Two sets of elements, one including N, K, S, Cu, and Zn (group 1) and another including Mg, Mn and Se (group 2) were major contributors towards the variance in the elemental concentrations in leaf tissue. Changes in N concentration were counterbalanced by changes in concentrations of the elements of group 2. Mn showed antagonism towards the elements of group 1. No definite grouping of elements was apparent in the principal components for inflorescence tissue.