Aims of the study: To determine the prevalence of intron 22 and intron 1 inversions of factor VIII gene in Croatian population in patients with haemophilia A and to investigate the frequency of inhibitors in patients with present mutations. Study design: The study is constructed as a cross-sectional study. Participants and methods: The data of 80 haemophilia patients were taken from medical documentation. Study included 80 patients, 68 of whom (85%) have a severe type of haemophilia A, 5 (6.3%) have a moderate type of the disease and 7 (8.8%) patients have the mild type. Mutations are proven by using the LD-PCR method and activity of FVIII and the presence of inhibitors to FVIII by standard coagulation tests. Results: From 80 haemophilia A patients, 28 suffer from the severe type of haemophilia A, inversion of intron 22 has been detected with the frequency of 41.2%. In 29 patients with detected intron 22 inversion only 37.5% have inhibitors of FVIII. Mutations of intron 1 have not been detected in any of the examined patients. There is a statistically significant usage of FVIII concentrates in patients with the severe type of the disease in comparison to the moderate and mild type, while presence of inversion 22 does not meet the statistical difference in the usage of the drug. Conclusion: The prevalence of the most common mutation in a severe type of haemophilia A, inversion of intron 22 is 41.2%. The prevalence data of inversion 22 and intron 1 are investigated for the first time in Croatian population of patients with haemophilia A. Linkage analysis between mutations and presence of inhibitors to FVIII in our patients with haemophilia is 35.7%, which has already been already observed in the literature.