A simple model has been developed that demonstrates that heliospheric X-ray emission can account for about 25%–50% of observed soft X-ray background intensities. Similar to cometary soft X-ray emission, these X-rays are thought to be produced in the heliosphere due to charge transfer collisions between heavy solar wind ions and interstellar neutrals. A more complex model has now been developed to take into account temporal and spatial variations of the solar wind and interstellar neutrals. Measured time histories of the solar wind proton flux are used in the model and the results are compared with the ‘long-term enhancements’ in the soft X-ray background measured by ROSAT for the same time period.