New approaches to assess energy intake (EI) may have advantages over traditional written methods, but validity of these emerging methodologies must be demonstrated. This exploratory study compared EI obtained using a hand-held personal digital assistant (PDA) and traditional written records with total energy expenditure measured by doubly labeled water (TEE_DLW). Twenty-six volunteers (aged 23±4 years, body mass index [calculated as kg/m²] 24±2) participated in a randomized (either PDA or written record group) and matched (for sex, age, and body mass index) study for 7 consecutive days between June 2005 and April 2006 to record EI. Group comparisons were made with t and Mann-Whitney U tests. Bland-Altman plots were used to compare limits of agreement between methods. Volunteers remained weight stable during the study period (0.2±0.8 kg; P>0.05). Reported EI by written record and PDA were similar to TEE_DLW; 105% vs 92% of TEE_DLW, respectively (P>0.05). There was a significant relationship between reported EI by PDA and TEE_DLW (r=0.60, P<0.05), but not for written record (r=0.45, P>0.05). Limits of agreement indicated both written record and PDA had large variability (range 1,394 to −1,472 kcal/day). Findings suggest the bias in using a PDA is similar to that observed when using a written record for estimation of EI in weight-stable volunteers.