This study was conducted to determine the temporal pattern of lateralized congestion of the nasal mucosa. Thirteen female and 15 male healthy subjects (median age, 27 years) were examined using magnetic resonance imaging (MRI) at a 0.2-T system every 30 min. Contiguous coronal T1-weighted imaging was performed covering the entire nasal cavity. Subjects were investigated over periods of up to 4 h (n = 28) or up to 14 h (n = 6), respectively. Nasal cavity volumes were measured by manual segmentation of the acquired images and summation of areas. Additionally, olfactory testing was performed. All subjects exhibited normal olfactory function. The minimum unilateral volume of the nasal cavity during congestion was 2.2 cm3, and maximum volume during decongestion was 17.0 cm3 (mean, 7.7 cm3). Seven subjects exhibited minor fluctuation of their nasal volumes. In contrast, 21 subjects showed nasal cyclicity. Maximum fluctuation of the volume of the nasal cavity was found in the vicinity of the turbinates in the central and posterior nasal cavity. The length of the nasal cycle showed high variability and was in the range of 180 to 280 min. No correlation was found between nasal volumes and olfactory scores. Using MRI, the present study is the first to report differences with regard to both the presence of a nasal cycle in an individual subject and the length of the nasal cycle. Considering that nasal congestion is of significance to human well-being, the present observations may influence clinical decisions.