OBJECTIVE: To develop a model that can predict the chance to conceive spontaneously in subfertile couples. DESIGN: In a cohort study, a consecutive series of patients consulting infertility was followed up. We related information from previous history, physical examination, postcoital tests (PCT), semen analyses, and sperm penetration meter tests with the occurrence of a spontaneous pregnancy. SETTING: Fertility center in a university hospital. PATIENTS: Nine hundred ninety-six couples consulting for infertility due to cervical hostility, male subfertility, or unexplained infertility. INTERVENTIONS: None. MAIN OUTCOME MEASURE(S): Time between intake and occurrence of the first spontaneous pregnancy. RESULTS: Information from the previous history (duration of infertility, primary or secondary female infertility, age of the woman, fertility problems in male's family), the percentage motile sperm in the first semen analysis, and the result of the first PCT are sufficient to predict the chance to conceive. A pocket chart is presented for easy use of the model. CONCLUSIONS: With a limited amount of diagnostic information, the chance to conceive spontaneously can be predicted.