In this study we analyzed Spanish Post-Heart-Transplant Tumour Registry data for adult heart transplantation (HT) patients since 1984. Median post-HT follow-up of 4357 patients was 6.7 years. Lung cancer (mainly squamous cell or adenocarcinoma) was diagnosed in 102 (14.0% of patients developing cancers) a mean 6.4 years post-HT. Incidence increased with age at HT from 149 per 100 000 person-years among under-45s to 542 among over-64s; was 4.6 times greater among men than women; and was four times greater among pre-HT smokers (2169 patients) than nonsmokers (2188). The incidence rates in age-at-diagnosis groups with more than one case were significantly greater than GLOBOCAN 2002 estimates for the general Spanish population, and comparison with published data on smoking and lung cancer in the general population suggests that this increase was not due to a greater prevalence of smokers or former smokers among HT patients. Curative surgery, performed in 21 of the 28 operable cases, increased Kaplan–Meier 2−year survival to 70% versus 16% among inoperable patients.