Several studies suggest that the prevalence of allergic diseases have increased worldwide in recent years. However, in Mexico, those diseases have not been assessed throughout time. The aim of this study was to determine whether there has been a change in the prevalence of childhood asthma, eczema, and atopic rhinitis in Mexican schoolchildren. Following the methodology recommended by the International Study of Asthma and Allergy in Childhood, we performed two cross-sectional assessments (1995/2002) using a standardized questionnaire-based survey answered by the parents of schoolchildren aged 6-8 years and 11-14 years randomly selected from schools in Cuernavaca, Mexico. The prevalence of asthma diagnosed by a doctor was 5.8% (95% CI, 5.2, 6.4) for 1995 versus 9.1% (95% CI, 8.3, 10.0) for 2002, with a greater prevalence in children aged 6-8 years in 2002 (5.7% versus 9.0%). No significant differences were found over time for wheezing in the last 12 months: 7.7% (95% CI, 7.1, 8.4) in 1995 and 8.0% (95% CI, 7.3, 8.8) in 2002. The prevalence of nasal and eye symptoms without colds was slightly higher in 1995 than it was in 2002: 9.9% (95% CI, 9.1, 10.7) versus 8.2% (95% CI, 7.4, 9.0), respectively. The results suggest an increase in the prevalence of asthma diagnosed by a doctor. However, no difference was observed in the prevalence of wheezing in the last 12 months, which may indicate a possible absence of "epidemic asthma" in the city of Cuernavaca among schoolchildren.