In view of the magnitude of the errors which may occur in single ages, it may be preferable to combine the figures into 5-year age groups. This approach laminates the irregularities but several important types of errors remain in age data even when the data are grouped. In addition to some residual errors due to digit preference, 5-year or 10-year data are affected by other types of age misreporting also. The mathematical graduation . is a technique which will directly provide corrections of census figures for age errors. Four methods of graduation maintaining the census totals for 10-year age groups are applied here. These methods are Carier-Farrag ratio method. Quadratic interpolation, and oscilatory interpolation (Sprauge and Karup-King). Another method proposed by the United Nations, specially for underdeveloped countries, is also used. The various sets of figures obtained by mathematical graduation are compared with the original census counts to indicate the extent of age misreporting of 5-year age group shown by each method'. Data from census 1972, N.W.F.P. is taken as a case study.