Background The primary aim of this study was to evaluate the level of diagnostic overlap between daytime ambulatory blood pressure (BP) monitoring (DT-ABPM) and 24-hour ambulatory BP monitoring (24-h ABPM) in detecting masked hypertension (MH). Methods This is a prospective study that was performed in a sample of 196 soldiers aged between 21 and 50 years (without a history of hypertension) undergoing ABPM testing. The diagnosis of MH based on DT-ABPM defined as (office blood pressure (OBP) <140/90 and DT-ABPM ≥135/85) was compared with the 24-h ABPM defined as (OBP <140/90 mm Hg and 24-h ABPM ≥130/80 mm Hg). We critically analyzed the results to see the agreement between the two methods. Results The number of subjects classified as having MH based on both DT-ABPM and 24-h ABPM, only on 24-h ABPM, and only on DT-ABPM were 11 (5.6%), 29 (14.8%), and 18 (9.2%), respectively. The sensitivity, specificity, and positive and negative predictive values for DT-ABPM in detecting MH were: sensitivity = 100% (95% CI: 97.82% - 100%), specificity = 62.07% (95% CI: 42.26% - 79.31%), PPV = 93.82% (95% CI: 90.50% - 96.03%), and NPV = 100%, respectively. The level of agreement between DT-ABPM and 24-h ABPM in diagnosing MH was 94.4% and discordance in 5.6% (11/196); (kappa=0.736, p < 0.001). Conclusion The sensitivity, specificity, positive and negative predictive values all showed agreement between the two BP methods to confirm the diagnoses of MH. DT-ABPM can be used as an alternative to the 24-h ABPM. DT-ABPM eliminates sleep disturbance attributable to ABPM and maximizes patient compliance with the ABPM test. A further larger trial is needed for more confirmation and to affect the guidelines for using daytime ABPM.