Jane Eyre by Charlotte Brontë (1847) is one of the most influential books in the Victorian period, especially in women’s history, with its groundbreaking female protagonist who is not the usual passive female character but takes her future into her own hands. Considering that Charlotte Brontë wrote about strong female characters it is not surprising that she touches upon the Victorian madwoman issue. By looking at the historical background of insanity within women in the nineteenth century, and examining Bertha Mason’s madness and personality, I investigate Jane’s behaviour in comparison to Bertha's in my thesis, with special attention on racial and social similarities and differences. In the first chapter, I introduce the historical background of women and mental disorders in the nineteenth century to understand how Victorians treated mad women. Secondly, I present Bertha Mason, the main "mad woman" in Jane Eyre, who is locked in the attic from the moment she is deemed mad. Thirdly, I describe Jane Eyre, the protagonist of the novel, explore her mental state in relation to Bertha’s and argue that she could have received the same harsh treatment if it was not for her race and Rochester’s love for her. Lastly, I compare Bertha and Jane, arguing that Bertha is Jane’s dark double and examining how Bertha executes Jane’s secret desires.