Five hundred sixty-nine subjects routinely underwent skin prick tests for latent sensitization to latex. The study of risk factors included skin tests to inhalant allergens, to diagnose atopy, and a questionnaire aimed at revealing frequent exposure to latex such as the wearing of gloves, multiple surgical procedures, or urinary catheterization. The subjects were categorized into five groups: group I, subjects with no risk factor (n = 272); group II, nonatopic subjects exposed to latex (n = 73); group III, atopic subjects not exposed (n = 180); group IV, exposed atopic subjects (n = 44); and group V, subjects with a history of intraoperative anaphylactic shock caused by latex (n = 13). Twenty-five subjects had spina bifida and were in either group II (14 subjects) or group IV (11 subjects). The questionnaire identified a probable allergy to latex in 18 subjects: 16 cases were confirmed by skin test, but responses were not informative in 23 patients who were sensitive to latex. Positive prick tests to latex were obtained in 0.37% of group I, 6.85% of group II, 9.44% of group III, and 36.36% of group IV. Of the children with spina bifida, 32% had positive skin test results. As risk factors, atopy and exposure were synergistic. We recommend predictive prick tests not only in children with spina bifida but also in any atopic subject or in any patient with a history of frequent exposure to latex. Latex could be considered a habitual allergen. The use of latex urinary catheters should be avoided in patients who are catheterized on a daily basis.