A series of 12 in vivo digestibility trials, using two-tooth Merino wethers were conducted on freshly-cut green kikuyu herbage. Samples of this herbage were analysed by proximate and acid-detergent analysis. A close relationship was found between crude fibre (CF) and acid-detergent fibre (ADF) (ADF = 20,06 + 0,56CF; r = 0,607; P < 0,001). An outstanding feature of these data is the positive correlation between the fibre fraction and digestible organic matter (DOM) as well as a negative correlation for the nitrogen fraction on DOM. The nitrogen fraction was found to be negatively associated with the digestibilities of the nitrogen-free extract and fibre fractions which comprise 75% of the herbage.