This paper deals with the results of a field experiment conducted in order to study dry matter production and macronutrient accumulation in two cassava cultivars 'Branca de Santa Catarina' and 'IAC Mantiqueira'. Plants received an uniform dressing of N, P2O5 and K2O of 40, 80 and 60 kg/ha, respectively as ammonium sulphate, simple superphosphate, and muriate of potassium; N was top dressed 60 days after emergence. Two irrigations were provided in the beginning of the growth cycle. Plants were sampled and analysed for growth parameters and macronutrient composition in six occasions with 60 day intervals: The main conclusions and relevant data were as follows: 1. there was a statistical difference in root production of the two cultivars;.maximum dry matter accumulation took place in the period pf 120 - 180 days after emergence; 2. extraction of macronutrients was the same in the two cultivars, except for P; export was different only in the case of K and S.