In 2006 the Iranian national cancer registry reported that Kohgiluyeh and Boyer-Ahmad, a small province located in the southern part of the country, had a low incidence rate of almost all types of cancer. In a population-based cohort study, data on 660 cases of cancer in Kohgiluyeh and Boyer-Ahmad province were analysed after ICD codes had been rechecked and duplicates removed. Over the period 2007–2009 the annual average incidence rate of all cancers rose significantly by 53.0% and 115.1% in men and women respectively. Cancers of the prostate, thyroid, bladder and soft tissues decreased over the study period. Despite the recorded rise, the incidence rates for different sites of cancer (except for skin cancer) were significantly lower compared with their corresponding national rates for 2006. The results point to improvements in the cancer diagnosis and registry in the province, although real changes in cancer incidence over the period cannot be ruled out.