BACKGROUND: In the last decades, the incidences of oesophageal and gastric cardia adenocarcinoma increased rapidly in the Western World. We investigated the association between BMI, height and risk of oesophageal and gastric cardia adenocarcinoma. METHODS: The Netherlands Cohort Study was initiated in 1986. All participants (n=120,852), aged 55-69 years, completed a self-administered questionnaire. Cases were identified through annual record linkage with the Netherlands Cancer Registry. After 13.3 years of follow-up, excluding the first follow-up year, complete data from 4552 subcohort members, 133 oesophageal and 163 gastric cardia adenocarcinomas were available for case-cohort analyses. Incidence rate ratios and corresponding 95% confidence intervals were estimated using Cox proportional hazard models. RESULTS: The RRs (95% CI's) of oesophageal adenocarcinoma were 1.40 (0.95-2.04) and 3.96 (2.27-6.88) for overweight (BMI 25.0-29.9 kg/m2) and obese subjects (BMI >=30.0 kg/m2), respectively, compared to subjects with normal weight (BMI 20.0-24.9 kg/m2). For gastric cardia adenocarcinoma, these RRs were 1.32 (0.94-1.85) and 2.73 (1.56-4.79). Also change in BMI during adulthood was positively associated with the risk of oesophageal and gastric cardia adenocarcinoma (p trend 0.001 and 0.02, respectively), while no association was found with BMI in early adulthood (p trend 0.17 and 0.17, respectively). None of the tumour types investigated was significantly associated with height. CONCLUSIONS: These results confirm higher risks of oesophageal and gastric cardia adenocarcinoma with increasing BMI. This implies that the increasing prevalence of obesity may be one of the explanations for the rising incidences of oesophageal and gastric cardia adenocarcinoma in the Western world.