This paper suggests that the incidence of poverty is severely underestimated in Greater Cairo. This is because poverty lines are set too low in relation to the costs of the most basic of needs in the city and because census data that inform household surveys, on which poverty line studies are based, under-count the people living in ashwa’iyyat (informal settlements). The paper assesses the costs of food and non-food needs in eight informal areas in Greater Cairo and compares these costs with the allowances made for them in Egypt’s poverty lines (which are meant to indicate the income needed to afford these food and non-food needs). Those who live in ashwa’iyyat frequently pay more for many food items than those who live in some of Cairo’s most prosperous neighbourhoods. The food allowance in poverty lines fails to factor in the cost of a nutritious diet as it is based on the actual diets of the poor. All households interviewed face non-food costs that are much higher than the allowance for these in even the more generous poverty lines. Yet, they still live in very poor conditions. Such costs include rent, keeping children in school, transport (for income earners and students), health care, water, sanitation and electricity. Raising the value of poverty lines to adequately reflect the real costs of food and non-food needs would considerably increase the incidence of poverty in Greater Cairo. Poverty lines must be set at levels that make sufficient allowance for the real costs of living: enough and nutritious food, reasonable quality accommodation, water, sanitation, electricity, keeping children in school, transport, health care and medicines when needed.