We present the studies conducted on sodium-bioglass/polythene (Na-BG/PE) composites and their bioactivity in simulated body fluid (SBF). Several compositions of Na-BG/PE composites were made by hot pressing and the activity studies of the samples were carried out by immersing the composites in SBF for periods of 7, 14, and 21 days. The activity of the samples was confirmed by the cauliflower-like growth of phosphates on the surface of the samples observed in an environmental scanning electron microscope and further confirmed by energy-dispersive X-ray spectrometry (EDS). X-ray diffraction showed the presence of various types of calcium phosphate phases. Ionic movement was observed by inductively coupled plasma atomic emission spectroscopy from the sample to the SBF solution and the reverse trend was observed on the surface of the sample by EDS. Modulus of rupture of the composites increased when the polymer content was increased up to 30% by weight of polythene, beyond which the processing of composites became difficult.