I have an illness and I want to marry. I just want to know if I am obliged to tell this to my future wife.

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

A believer must be satisfied with Allah's Qadr (Divine Destiny) and be patient; he has to sacrifice in anticipation of Allah's reward and has to know that illnesses and trials which befall him are for something that Allah wills as well as being a means to raise his status and wipe out his misdeeds.

Thus, if your health problems and troubles may affect your marital life, then you have to inform your wife to be fully aware of her position.

Allah knows best.