The few studies carried out on the effects of Ramadan fasting (RF) on spirometric values present contradictory conclusions. This study aimed at assessing whether RF affects healthy adults’ spirometric values. Twenty-nine nonsmoking healthy males (M ± standard error of mean [SEM] of age: 27 ± 1 years) who fasted during Ramadan (June 29-July 28, 2014) volunteered to the study. Three periods (before-Ramadan [June 23-25], mid-Ramadan [July 14-16] and after-Ramadan [August 11-14]) were selected for spirometry measurements that were consistently performed 5.5 to 3.5 hours (between 15:00 and 17:00 hours) before fasting break. Assessment sessions comprised following: weight (kg), forced vital capacity (FVC), first second expiratory volume (FEV₁), FEV₁/FVC, peak expiratory flow (PEF), maximal mid expiratory flow (MMEF), and forced expiratory flow rate at the x% of FVC to be exhaled (FEF_x%). Spirometric data were expressed in percentages of reference values. Results were analyzed by applying repeated measures analysis of variance. The M ± SEM of weight (before-R: 81.6 ± 2.8 kg, mid-R: 80.8 ± 2.9 kg, after-R: 81.2 ± 2.9 kg), FEV₁ (before-R: 99 ± 2%, mid-R: 98 ± 2%, after-R: 98 ± 2%), FVC (before-R: 103 ± 2%, mid-R: 101 ± 2%, after-R: 101 ± 2%), PEF (before-R: 112 ± 3%, mid-R: 113 ± 2%, after-R: 114 ± 3%), MMEF (before-R: 83 ± 3%, mid-R: 83 ± 3%, after-R: 82 ± 3%), FEF_25% (before-R: 90 ± 5%, mid-R: 89 ± 6%, after-R: 87 ± 6%), FEF_50% (before-R: 94 ± 4%, mid-R: 91 ± 4%, after-R: 93 ± 3%), and FEF_75% (before-R: 108 ± 3%, mid-R: 111 ± 2%, after-R:111 ± 3%) were not significantly influenced by RF. To conclude, RF did not bring about any significant changes in the spirometric values of nonsmoking healthy adult males.