The dairy sludge elimination is still not optimized in Reunion Island as it is currently dumped in landfills. The aim of this study is to investigate the co-composting of dairy sludge with cattle manure. Three heaps were formed using cattle manure mixed with dairy sludge in the following proportions: M - 1 + 0, S1 -2/3 + 1/3 and S2 - 1/2 + 1/2. The heaps were turned after 21 days. Total composting time was 142 days. During the experimentation, temperature remained high and above 55°C during 46 days for the pure manure pile M, 32 days for S1 pile and 36 days for S2 pile. During composting, M has lost 69% of its fresh mass and 64% of its initial volume while 71% and 44% respectively for S1 and 68% and 49%, respectively for S2. Heaps have lost from 44% to 49% of the initial organic matter and the windrows formed with sludge lost more nitrogen than the pure manure one (M - 52%, S1 - 69% and S2 - 66% of its initial nitrogen).