Klotho is a new identified anti-ageing gene with tumour suppressor activities. Current data suggest that there is a tight relationship between Klotho protein and growth hormone (GH)/insulin-like growth factor-1 (IGF-1) axis.This study aimed to investigate the possible association of Klotho gene polymorphisms with acromegaly and to assess whether these polymorphisms contribute to clinical characteristics, comorbidities and biochemical variables in these patients.The study included 52 patients with acromegaly and 52 unrelated healthy subjects. The Klotho G395A and C1818T polymorphisms were assessed by Sanger sequencing. Serum levels of sKlotho were determined by ELISA method.Subjects carrying GA genotype of Klotho G395A polymorphism had 3.27 times higher risk of developing acromegaly [odds ratio (OR), 3.27; 95% confidence interval (CI): 1.37-7.81; p = .023]. The A allele of G395A was significantly associated with acromegaly risk (OR, 2.27; 95% CI: 1.1-4.72; p = .022). No association was observed between the studied polymorphisms and disease characteristics including age at acromegaly diagnosis, size of adenoma, baseline GH and IGF-1 concentrations, and final outcome. G395A polymorphism was associated with the presence of malignancy (OR, 2.24, 95% CI: 1.63-3.08; p = .019) and colorectal polyps (OR, 1.99; 95% CI: 1.02-3.88; p = .047) in patients with acromegaly. Serum sKlotho levels were significantly higher and correlated with GH and IGF-1 levels among acromegaly patients. There was no association between the studied polymorphisms and sKlotho levels.Klotho G395A polymorphism is associated with acromegaly susceptibility and increased risk of malignancy and colorectal polyps in these patients.