Background information: Many studies have been developed revealing normal measurementsrnof adenoid size and adenoid to nasopharyngeal Ratio (ANR). The lateral radiograph is a commonrninvestigative modality. However, the literature is diverse and controversial. Lateral x-raysrnundertaken for purposes other than suspected upper airway way obstruction at Tikur AnbessarnSpecialized Hospital (TASH) are assumed to be inadequate for the sample size needed for thisrnstudy. Moreover, the risk of radiation exposure makes the use of lateral xâ€“ray requests solely forrnthis study unethical. Therefore a cross-sectional imaging study was done.rnrnObjective: To determine the accurate size of the mean adenoidal size and ANR rnrnMethodology: A quantitative prospective cross-sectional study was conducted in 114 patientsrnaged from 4-12 years (divided into three age groups), who underwent CT of the neck or head &rnneck at Tikur Anbessa Specialized Hospital (TASH), Addis Ababa, Ethiopia. Subjects who hadrnsymptoms of upper airway obstruction or sleep-disordered breathing were excluded objectivelyrnusing Obstructive Sleep Apnea score (OSA). Linear measurements of adenoid size andrnnasopharyngeal depth were done along a reconstructed sagittal section and the ANR wasrncalculated according to the Fujioka method.rnrnResults:rnrnWe studied 114 children aged 4-12 years who were divided into three sub-groups namely group Irn(4-6 yrs), II (7-9 yrs) and III (10-12yrs). We calculated the mean adenoid thickness, meanrnnasopharyngeal depth and calculated the mean ANR of each groups. The statistically analyzedrnmean ANRs were 0.416, 0.397 and 0.395 for Group I, II, and III respectively with the highestrnvalue of 0.66 detected in group I. The mean adenoid size were measured to be 8.34, 8.41, andrn9.42 for the age groups I, II and III respectively. We found that both the mean adenoid size andrnthe ANR did not show significant differences between each groups but there was a progressivernincrease of the nasopharyngeal depth as the age progress across the different groups.rnrnConclusion: rnrnAdenoid to nasopharyngeal ratio (ANR) was the most consistent radiologic parameter whenrnsubjectively compared with previous x-ray based studies. Therefore we strongly recommend thernuse of ANR rather than the mere use of the adenoid size or the nasopharyngeal space depthrnparticularly when evaluating the degree of nasopharyngeal obstruction by enlarged adenoids.rnHowever radiologists and responsible physicians should use lateral x-rays cautiously as plain rnfilms may overestimate or underestimate the adenoid shadow and nasopharyngeal space depthrndue to superimposition of adjacent structures.