Four composites of hydroxyapatite/hydrolyzed polyacrylamide (HAP/HPAM-n) were prepared using an in situ wet chemical method. The synthesis was performed by preparing a suspension of calcium in a copolymer solution having a known HPAM concentration. Phosphoric acid was added dropwise to each suspension to obtain HAP/HPAM-n composites. The effect of initial copolymer amount on the composite properties was investigated using XRD, FTIR, TGA, and SEM/EDS analysis. The obtained results were compared to the HAP sample synthesized under the same conditions and without copolymer. HPAM amount in the composite affects the retention of methylene blue (MB) dye. The result shows that the increase of HPAM in the material leads to the increase of the dye retention capacity. Therefore, the composite prepared with a higher copolymer amount was selected to study the effects of different parameters on the dye removal including contact time, concentration, pH, temperature, and composite regenerations. We deduce in this work that the composite HAP/HPAM-75 is a good candidate for MB dye retention from aqueous solution with a maximum removal capacity of 435.6 mg g$^{-1}$ and the possibility of its reuse for several times.