Objectives: Menopause, the permanent cessation of ovarian activity, is part of normal aging, resulting in climacteric symptoms for most women, particularly in Western countries. The objective of the present study was to analyse risk factors for onset of menopausal symptoms.Methods: Analyses were based on the 28,118 women participating in the French E3N cohort study who reached menopause between 1990 and 2000. Questionnaires were sent every 2 years, and specifically enquired about use of hormonal treatments, reproductive factors, smoking status, anthropometric measurements, dietary habits and personal medical history, including onset of menopausal symptoms. Hazard ratios were computed from multivariable Cox proportional hazard models with age as the time-scale.Results: The risk of onset of menopausal symptoms was negatively associated with education level and with some hormonal and reproductive factors (usual duration of menstrual cycles, parity and current use of oral contraceptives). A decrease in risk was found in those with underweight, overweight and obesity, but only in post-menopause. The risk was positively associated with smoking and alcohol consumption; it was also positively related to certain frequent medical conditions (depression, migraine, benign thyroid disease, atopy), possibly due to underlying common mechanisms such as the influence of vaso-active substances. Among dietary factors, rapidly absorbed sugars and snacking were positively associated with the risk of onset of menopausal symptoms.Conclusions: Onset of menopausal symptoms seems to be affected by various reproductive, hormonal and environmental factors. Some of them are modifiable, which may allow suggesting recommendations. (C) 2008 Elsevier Ireland Ltd. All rights reserved.