A laboratory work was conducted to monitor two composting systems, aerobic and anaerobic for 9 months. Sugarbeet residues vehether resulted from haulms. preparation the roots in field and before squeezing to obtain sugar were collected, air dried and chopped into peces one inch long. The whole quantity was divided Into Iwo porticos. One of them was composted under aerobic and the other under anaero-bic conditions. Samples of each system were taken after 0. 7, 15 days then monthly up to 9 months. Results showed that organic matter content decreased with time of composting in a rate higher in case of aerobic compost than in anaer-obic one. Humus and organic acids Increased with time of composting. Their concentrations under anaerobic conditions were higher than those under aerobic when the period of composting was longer than 6 months. Total nitrogen increased. In the same lime. UN ratio narrowed gradually by time of composting. That ratio was more wide in anaerobic than in aerobic compost. Ammonification process was active through lime and produced more ammonia in anaerobic case. Nitrification activi-ty was detected only in aerobic conditions. Total phosphorus and total potassium followed the same trend of total nitrogen. Ratios of C/P and CM were almost similar to those of C/N. Ash per cent el decomposed material increased. pH of compost decreased slowly In aerobic case but under anaerobic condition, It was more acidic after 9 months. Total sol-uble salts in the mixture at 0 time was about 2.1%. That percentage in-creased gradually recording more high ninny In compost of anaerobic condition up to limes of its beginning. Soluble sodium and potassium behaved In similar trend of total soluble salts. The increases in total sol-uble salts resulted from more soluble Cr. Water holding capacity in composting samples revealed gradual increases under two composting systems up to 15 days in aerobic versus 60 days in anaerobic system to-lowed by a decrease in both cases As for moisture content, it gradu-ally increased with time of composting under both systems, but it was higher under anaerobic conditions.