Depth resolved positron annihilation measurements were carried out on 85 keV and 1 MeV nitrogen ion implanted InP samples. The defect sensitive S-parameter and R-parameter values for the low energy implantations confirm the presence of monovacancies up to a dose of 1015 cm-2 and coexistence of monovacancies and divacancies for 1016 cm-2 dose sample. Corroborative glancing incidence x-ray diffraction measurements on the highest dose sample revealed that the sample is amorphized. For high energy implantation, it is found that vacancy-defects are present right from the near-surface region and these defects are identified to be monovancancies, based on the observed S- and R-parameters. A comparison of the results for the low and high energy implantations is made. © 2005 IOP Publishing Ltd.