In non-small-cell lung carcinoma (NSCLC) there are gender differences. The female gender is associated with more adenocarcinomas (ADCA), among both smokers and non-smokers compared to men. Women with NSCLC have a better prognosis compared to men, regardless of other factors. A possible role for oestrogen receptor (ER) signalling has been proposed. The role for ER beta in NSCLC is still not clear, especially concerning the impact of smoking. In a material of NSCLC (n = 262), ER beta and cyclins A1 and A2 were studied by immunohistochemistry on formalin-fixed paraffin embedded tissue. In 137 of those cases, frozen material was available, on which expression analysis of ESR2 (ER beta) and cyclin A1 were performed. Data were correlated to histology, gender, smoking habits, stage and clinical outcome. ER beta was expressed in 86% of the cases. ER beta was most frequently expressed in Stage I ADCAs, especially in male subjects. A correlation between ER beta expression and cyclins was observed in ADCA, also with a male predominance. ER beta transcripts had a positive prognostic impact in ADCA. ER beta transcripts were increased in NSCLC among smokers compared to non-smokers. In conclusion, our data support a role for ER beta in lung ADCAs, proposing a role for ER beta in lungcarcinogenesis, especially among smokers.