This study was designed to investigate the influence of the predictive power of the genetic test, the disease's controllability, and gender on the intention to take a predictive genetic test. Another aim was to examine the certainty of the intention to take the test. Nine scenarios were presented to a convenience sample of 121 men and women. Each scenario described a hypothetical and devastating late-onset disease and manipulated the level of disease controllability and test predictive value. The more predictivity the test offered and the more controllable the disease, the more the subjects were interested in being tested and the more certain their decision to take the test. Men's decisions were more positive than women's. There were also interactions between disease controllability and gender and between disease controllability and test predictivity. It seems that the factor that most influences the decision not to take the test is low disease controllability. This effect is more pronounced in women. Gender differences in decision making and information processing may be pertinent. The data show a marked gap between the decision itself and the certainty of that decision. The strength of the decision may be a better predictor of actual test uptake than the direction of the decision.