The latest victim was an 18-year-old woman from a province north of Cairo, who was admitted to hospital on Monday.
Egypt has so far reported 12 human bird flu cases.
"An 18-year-old woman from Ashmoun in Monoufiya has died of bird flu, bringing the number of deaths to four from the 12 people who have been infected," MENA quoted Hatem el-Gabali, the country's health minister as saying.
The woman had been admitted to hospital after handling domestically kept birds infected with bird flu, he added.
She had been on an artificial respirator since she was admitted, and had died despite receiving Tamiflu, an anti-viral medication thought to be the best method of fighting bird flu in humans.
The disease, which has killed at least 109 people worldwide, has spread since 2003 from Asia to Europe, the Middle East and Africa. While mainly affecting animals, scientists fear the disease could mutate into a form that can pass easily between humans, sparking a pandemic.
Bird flu was detected in birds in Egypt in February and the first human infection was reported in mid-March. The World Health Organisation (WHO) has already said it is concerned about the disease's human toll in a relatively short period of time.
Egypt's efforts to contain the disease have been hampered by people breeding poultry in their homes despite a government ban, because they say they are too poor to slaughter their birds.
Poultry is an important source of income and protein for millions of Egyptians.
Women, who make up all of Egypt's fatalities, are often responsible for slaughtering and cooking domestic poultry, and the government has called for more awareness about bird flu among women to protect themselves and their families.
The WHO, which carries out additional tests after initial government testing, has so far confirmed four of Egypt's total cases including two of the deaths.