This study investigates the relationship between health and marital status, focusing particularly on older persons, using data on reported long-term illness rates from the Samples of Anonymised Records (SARs) drawn from the British Census. Until about age 70, long-term illness rates are generally lowest for those in first marriage, followed by the remarried, with intermediate values for the widowed and divorced, and highest for the single. Beyond age 75 for both sexes, single people in the private household population report the lowest illness rates, but when the institutionalized population is included single people at older ages no longer appear to be the healthiest group. This is because at older ages increasingly high proportions of those with long-term illness are in institutions, disproportionately so for single people, explaining why such cross-overs have been found in analyses of private household populations. The health status of co-habiters is generally closer to the married than to other groups for both sexes.