Several correlational studies have suggested an association between stroke mortality rates and geophysical parameters, but none have assessed the influence of these parameters on stroke occurrence in a general population. We conducted a population-based study (2,195 stroke patients) to determine whether there are relationships between stroke occurrence and solar and/or geomagnetic activity. A multivariable logistic regression analysis was used to estimate the odds ratio (OR) and to identify the geophysical parameters of most importance; 95% confidence intervals (CI) were calculated for the variables studied. In a multivariate analysis, large fluctuations of solar (OR = 1.21; 95% CI 1.14–1.30) and geomagnetic activity (0R = 1.20; 95% CI 1.11–1.31) on the preceding day and low level of solar activity (OR = 1.14; 95% CI 1.08–1.21) on the day of stroke onset were independent predictors of stroke occur