Gallstone disease is a main public health problem. The overall prevalence data range from 3.9% in the pre-echographic era to 13.7% when ultrasonography was used as a diagnostic tool. This study is aimed to determine the prevalence of gallstone disease in a medium income level population in Lima, as well as the relationship with some risk factors: age, sex, familiar history and obesity. A total of 534 adult men and women from a medium economic level underwent ultrasonographic examination of abdomen for detection of gallstone disease (July 2003). The echographic evaluation was performed by 10 general surgeons trained in ultrasonography. Likewise, 4 risk factors--age, gender, familial history, and obesity--were analyzed. Pearson chi2 test (2-sided) was used with a probability of <0.05 for statistical significance and logistic regression analyses for assessment of confounding factors. The prevalence founded was 15%. Eighty-one of 534 participants had lithiasis. Compared to the age group under 30, the odds ratio for the 31 to 50 years and >50 years of age group was 0.9 and 1.1, respectively. The female-male ratio was 1.07 and the odds ratio 0.8. The prevalence of gallstone disease in people reporting a first-degree relative with lithiasis was 21%, whereas in participants without such a condition, it was 13%. On the other hand, a familial history was present in 38% of the lithiasis group and in 25% of the nonlithiasis group. The odds ratio for familial history was 1.8 (P = 0.01, 95% confidence interval 1.1-2.9). The prevalence of the disease for body mass index <24, 25 to 29, and higher than 30 was 17%, 14% and 13%, respectively. Compared to the reference group (body mass index <24), the other 2 groups (body mass index 25-29 and >30) both had a similar odds ratio, 0.8. Logistic regression analyses showed an odds ratio of 1.9 for familiar history (95% confidence interval 1.1-3.2), whereas the odds ratio of the overweight (body mass index 25-29) and obese group (body mass index >30) when compared to the normal group, BMI <24, was 0.7 and 0.9, respectively. The prevalence data for gallstone disease remain slightly higher than those previously reported. Although the familiar history was the only characteristic with a statistically significant positive relationship with lithiasis, additional studies are needed because few biases could not be completely avoided and some confounding factors were not controlled.