A greater use of clover based grassland systems seems likely in future as policies promoting more extensive use of land are adopted by Government at both national and EC level. At Aberdeen a comparison between clover-based and conventionally fertilised systems was carried out over six growing seasons from 1981. The objective was to compare the beef output from two similarly managed farmlets differing only in clover content and fertiliser input. Results are presented here for performance obtained from the grazed swards over this six year period.