Agusan del Sur registered a total population of 559,294 persons in Census 2000, an increase of 44,558 persons from 1995 Census of Population. This figure translated to an annual growth rate of 1.79 percent, a sudden decrease of 2.06 percentage points from that of the 1990 to 1995 period. The number of households also rose to 103,637, compared to 95,188 households from the 1995 figure. The average household size was 5.39 persons, the same as that of 1995 but higher than the national average of five persons.

The population of General Santos City, as of May 2000 was 411,822 persons. This was up by 84,649 persons as compared to 327,173 persons recorded in the 1995 Census of Population. For the period 1995 to 2000, the annual population growth rate for General Santos City was 5.05 percent, slightly lower than the 5.14 percent annual population growth rate during the 1990 to 1995 period. This was more than twice as much as the national annual population growth rate of 2.36 percent. If the current annual population growth rate of the province continues, the population of General Santos City was expected to double in 14 years.

The 2000 Census of Population and Housing (Census 2000) results showed that Cotabato City registered a total population of 163,849 persons, higher by 17,070 persons over the 1995 Census of Population (POPCEN) results. This figure recorded a 2.38 percent annual population growth rate, lower by 0.35 percentage point than the annual population growth rate during the 1990 to 1995 period. A corresponding increase on the number of households was also recorded at 31,227 households, higher by 4,134 households over the 1995 figure. This resulted to an average household size of 5.17 persons, slightly higher than the average household size (5.38 persons) recorded five years ago and the national average of five persons.