Abstract: A study on the effect of organic manure on seedling growth and development of Acacia Senegal was conducted at the Teaching and Research Farm of Faculty of Agriculture, Delta State University. There were 4 treatments in all namely poultry droppings, cowdung, piggery manure and topsoil (control treatment). The design adopted was completely randomized design with three replicates. Three months old seedlings of A. Senegal were transplanted into polypots containing representative samples of all the organic manure mix with topsoil according to treatments. The seedlings were assessed for height, leaf number and collar diameter. Total fresh and dry weights of the seedlings were also, determined at the end of the experiment. Analysis of variance revealed significant difference in the height growth, leaf number and collar diameter at 5% level of probability. Seedlings treated with cowdung had the highest average height of 17.15cm poultry droppings had the highest leaf number value of 21.20 and collar diameter value of 0.95cm. The highest leaf fresh weights (14.70g), Stem (34.00g) and Root (87.75g) were given by poultry droppings and were significantly different from the rest of the treatments at p< 0.05. Poultry dropping similarly produced 1.69 and 9.01 g for leaf, stem and root dry weights of A. Senegal seedlings, respectively. This study has demonstrated that poultry dropping is the most suitable for A. Senegal seedlings and in term of mineralization of the manure it is relatively fast when compared with cowdung and piggery. It is recommended that our local farmer should adopt the organic manure for ease of establishment of this species.