Current dietary protein requirement for adult males aged 65–75 are based on nitrogen balance data and suggest no difference in requirement between the elderly and young adults. Recent studies in young adult males using IAAO technique suggest that nitrogen balance estimates are too low. The objective of this study was to determine the protein requirement of elderly men using the IAAO technique with L‐[1‐ 13 C]‐phenylalanine as the indicator. Preliminary studies have been conducted in 3/7 (65–75 year old) men. Each received a minimum of 7 protein intakes (0.2 – 1.8 g.kg −1 .d −1 ) in random order after a 2 day adaptation providing energy at 1.7 times measured resting energy expenditure and protein at 1.0 g.kg −1 .d −1 . Oxidation study day diets were amino acid based liquid diets patterned after egg protein. The mean protein requirement was determined by visual inspection of the preliminary F 13 CO 2 obtained from the oxidation of L‐[1‐ 13 C]‐phenylalanine in response to graded protein intakes. Preliminary estimates suggest a mean protein requirement of 0.8 g.kg −1 .d −1 . This preliminary data suggest that the mean protein requirement of elderly men aged 65–75 years is 20% higher than current recommendations. This study was supported by a grant from the Canadian Institute for Health Research (CIHR).