High alcohol consumption is related to colorectal cancer (CRC). Our objective was to study associations between alcohol consumption and risk of CRC according to characteristics of aetiological pathways: the chromosomal instability (CIN) and the microsatellite instability (MIN) pathway. We classified CIN+ tumours (tumours with either a truncating APC mutation, an activating K-ras mutation or overexpression of p53), MIN+ tumours (tumours lacking hMLH1 expression) and CIN-/MIN- tumours (tumours without these defects). In the Netherlands Cohort Study on diet and cancer, 120852 men and women, aged 55-69 years, completed a questionnaire on risk factors for cancer at baseline (1986). Case-cohort analyses were conducted using 573 CRC cases with complete data after 7.3 years of follow-up, excluding the first 23 years. Adjusted incidence rate ratios (RR) and 95% confidence intervals (CI) were estimated. Compared with abstaining, alcohol consumption of >= 30 g/d was positively associated with the risk of CRC irrespective of genetic or molecular aberrations present, although statistical significance was not reached (RR 1.35 (95 % CI 0.9-2-0) for the CIN+ tumours, RR 1.59 (95 % CI 0.4-5-8) for the MIN+ tumours and RR 1.15 (95 % CI 0-5-2-7) for the CIN-/MIN- tumours). Beer, wine and liquor consumption were, independent of their alcoholic content, not consistently associated with the risk of CRC within the defined subgroups. In conclusion, our results indicate that a daily alcohol consumption of >= 30 g is associated with an increase in risk of CRC, independent of the presence or absence of the studied characteristics of different aetiological pathways.