Objective: To examine the prevalence of low serum folate and vitamin B12, in association with elevated serum homocysteine, in a representative sample of older Australians. Methods: During 1997-2000, 3,508 persons aged 50+ years were examined in a population-based cohort study conducted in two postcodes, west of Sydney, Australia. Of these, 2,901 participants (82.7%) provided fasting blood for estimates of serum folate, vitamin B12 and total homocysteine. Results: Low serum B12 (<185 pmol>/L) was found in 22.9% of participants and low serum folate (<6.8 nmol/L) in 2.3% of participants. Among those people with very low serum vitamin B12 (<125 pmol/L) and low serum folate, 51% had elevated homocysteine. Conclusions: Low serum levels of vitamin B12 and elevated serum homocysteine are relatively frequent in older Australians. Implications: Appropriate public health action should be considered to reduce the prevalence of low serum vitamin B12 and elevated homocysteine in older Australians.