Background and Objectives: Haller Cells (HCs) represent the abnormal migration of ethmoid cells that are located below the ethmoid bulla at the level of the upper wall of the maxillary sinus. Through their placement, the cells can exert a mass effect on the infundibulum of the maxillary sinus. The aim of our study is to investigate the prevalence of Haller cells in the Romanian population and to evaluate the relationship between this anatomical variation and chronic rhinosinusitis. Secondly, we want to morphometrically evaluate the impact of Haller cells’ presence in the drainage paths of the maxillary sinuses. Materials and Methods: We conducted a randomised retrospective study that included 255 consecutive multi-detector computed tomography (MDCT) scans of the head. To carry out a comparative evaluation of the association of Haller cells with chronic rhinosinusitis, we divided the patients into two subgroups, a seasonal-based sample, between November 2022 and January 2023, and June 2023 and August 2023, respectively. We report the mean ± standard deviation for the continuous variables. To compare the results, we used the following statistical tests: a chi-squared test and a paired Student’s t-test (one-tail). Results: Our study identified a high prevalence of Haller cells, namely in 128 out of 255 patients (50.2%). There were no statistically significant associations between the presence of HCs and the age and the gender of the sample, respectively. The unilocular morphotype predominates in unilateral shapes and in bilateral shapes as well (p = 0.002). Our study identified the correlation between the Haller cells and the chronic rhinosinusitis in both research samples: “Winter group” and “Summer group” (p = 0.0002 and p = 0.0001, respectively). Conclusions: It was determined that for 40 out of 42 patients, the presence of HCs changes the morphometric pattern of the infundibular maxillary sinus.