We investigate numerically and experimentally the modification of the spontaneous emission rate for micrometer.sized light sOurces embedded in a hollow-core photonic crystal fiber(HCPCF).The diameter of the light source isdeliberately chosen such that they could be easily introduced into the central hole of the hollow-core photonic crystalfiber by canillary force.The photoluminescence from the microparticles is measured by using an inverted microscopein combination with a spectrometer.The modification of the spontaneous emission rate is observed in a wavelengthregion where there is no band gap.The experimental observations ae consistent with the simulation results obtainedby the plane wave expansion and finite-difference time-domain techniques.