Polylactic acid (PLA)/hydroxyapatite (HAp) biocomposite microspheres with a specific core-shell structure for application as drug carriers were synthesised using an ultrasound field. In addition, the loading efficiency of clindamycin phosphate increased when the HAp content was increased to 30%. The effect of HAp content on enzymatic degradation of PLA/HAp microspheres loaded with clindamycin phosphate was that the degradation rate increased with increasing HAp content. Apatite formed on the surfaces of the PLA and PLA/HAp microsphere loading of clindamycin phosphate showed Ca and P peaks in energy-dispersive X-ray spectroscopy (EDX) data. In addition, the PLA and PLA/HAp microspheres loaded with clindamycin phosphate did not show any cytotoxicity against the human lung fibroblast MRC-5.