To evaluate the trend in social inequalities in health in Spain between 1987 and 1995/97, we carried out a secondary analysis of the Spanish National Interview Surveys from 1987, 1995 and 1997. We studied less-than-good perceived general health and four chronic conditions--heart disease, diabetes mellitus, chronic bronchitis/asthma and allergies--by social class and educational level in men and women aged 25-74 years. Among men, the age-adjusted prevalence rate ratio of less-than-good perceived general health by social class decreased from 1.32 to 1.23 between 1987 and 1995,97: however, the prevalence rate ratio by educational level increased from 1.47 to 1.57. Among women, the prevalence rate ratio of less-than-good perceived general health increased between the first and second period as much by social class from 1.18 to 1.26, as by educational level--from 1.59 to 1.66. For heart disease the age-adjusted prevalence rate ratio by social class among men was 1.12 in 1987 and 0.72 in 1995/97, while the prevalence rate ratio by educational level was around I in both periods, among women, the prevalence rate ratio for heart disease by social class was the same in 1987 and in 1995/97, but the prevalence rate ratio by educational level increased between the first and second period. For diabetes mellitus and chronic bronchitis/asthma, the prevalence rate ratio increased by social class and educational level between the first and second period in both men and women. Finally, the prevalence rate ratio for allergies was always < 1, although its magnitude increased between 1987 and 1995/97. In general, health inequalities were larger by educational level than by social class and were larger in women than in men. Inequalities in perceived general health, diabetes mellitus and chronic bronchitis/asthma increased in Spain between 1987 and 1995/97.