This paper engages with the global debate about the meaningfulness, validity and reliability of the poverty-line approach by examining the Egyptian poverty lines in relation to the reality of the lives of the urban poor in Greater Cairo. It reviews Egypt’s various poverty lines, and the data which inform them, and then questions their value in relation to the real costs of some basic living needs in eight of Greater Cairo’s informal areas in 2008. The paper concludes 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 even the most basic of needs, and because the household survey data which inform poverty-line studies under-sample people living in informal settlements, as they are based on census data which under-count the populations of informal areas.