Unoka dies of old age and sickness from swelling bowels, and symbolically of complacency.
The beginning of the book mentions that Unoka has died.
In his day he was lazy and improvident and was quite incapable of thinking of tomorrow. (ch 1)
Okonkwo's father Unoka is more interested in playing music and drinking than in farming. Okonkwo considers him lazy, and fears turning into him more than anything. Since Unoka never does any work, he borrows money from anyone who will give it to him and then laughs if they ask for it back. He owes so many people; he will never pay his debts.
When Unoka died he had taken to title at all and he was heavily in debt. (ch 1)
He is described as an “ill-fated” man. He died of “swelling in the stomach and the limbs” (ch 3), like the legend, and was not allowed to die inside the house. He dies with his flute.
Okonkwo’s goal in life is to be as little like his father as possible. He is ashamed of him, and hates him. He feels no pity. He blames his father for his own fate.