Cutaneous squamous cell carcinoma (SCC) is the most frequent skin cancer after organ transplantation. Currently, the pre-identification of transplant patients at increased risk for non-melanoma skin cancer remains difficult. To investigate the Hp polymorphism as a marker for the identification of a subset of patients with an increased susceptibility to develop SCC/Bowen's disease. Haptoglobin phenotyping was performed with haemoglobin-supplemented starch gel electrophoresis in 300 kidney transplant patients. High-performance gel permeation chromatography was used in case of low serum haptoglobin concentration. Cox regression analysis (adjusted for age, gender and Mediterranean origin) showed a significant association of the Hp 1-1 phenotype with a higher risk of SCC/Bowen's disease (P = 0.035) and multiple primary SCCs (P = 0.002). No significant difference between the Hp phenotypes was found for the development of Bowen's disease and SCCs in the first 10 years following renal transplantation. However, after a follow-up of >10 years, a significant association between the Hp 1-1 phenotype and the occurrence of Bowen's disease and SCC was reported (P = 0.002 and P = 0.001 respectively). This study shows an increased risk for the development of (multiple) SCCs in kidney transplant patients with the Hp 1-1 phenotype. This finding points to the role of Hp 1-1 phenotype as an important predictor in identifying a subset of patients with an increased need for preventive measures and is in agreement with the decreased anti-inflammatory capacity of this phenotype.