Aim. The aim of the study was to determine the ultrasonic gallbladder wall thickness in normal adult Nigerians so as to create standards for defining gallbladder abnormalities in Nigerians.
Method. Four hundred adults comprising 228 (57%) women and 172 (43%) men aged 16 - 78 years, who had normal clinical history and physical findings, were recruited. The gallbladder wall thickness was obtained in the supine, prone and right anterior oblique positions. Differences in gallbladder wall thickness were determined using the chi-square test, while the relationship between the ultrasound-measured gallbladder wall thickness and the subjects’ age, sex, height and weight were analysed using the Pearson product moment correlation. Normal ranges and related statistics were estimated and tabulated according to age group and sex.
Results. The mean age of the subjects was 32±13.2 years. The mean gallbladder wall thickness range was 1.8 - 2.8 mm±0.5mm. The thickness range for females was 1.7 - 2.7 mm±0.5 mm, and that for males was 1.9 - 2.9 mm±0.5 mm. There was a statistically significant difference (p<0.05) in the mean wall thickness between males and females. The mean body parameters (height, weight) of males were significantly greater than those of females (p<0.047, p<0.000 respectively). There was no correlation between gallbladder wall thickness and age and height of subjects (r=0.34, p<0.09).
Conclusion. Our study was able to establish population-specific ultrasonic values for gallbladder wall thickness in normal adults that can be reliably used as standard to define gallbladder abnormalities in Nigerians.

Key words: Ultrasonography, gallbladder wall thickness, adults.