A decade ago it was reported that childhood cancer incidence was higher in boys than in girls in many countries, particularly in those with low gross domestic product and relatively high infant mortality rates. Reports from developing countries have since agreed that socio-economic or cultural rather than biological factors are likely to be responsible. The aim of this study was to investigate further the association between cancer registration sex ratios and economic, social and healthcare related factors using more recent data (1998–2002). Sex rate ratios for 63 countries were calculated from data published in Cancer Incidence in Five Continents Vol IX. An increased M:F sex rate ratio was significantly associated with decreasing life expectancy (p=0.011), physician density (p=0.029), per capita health expenditure (p=0.005), GDP (p=0.001) and female education (primary school enrolment sex ratio, p=0.004; secondary school enrolment sex ratio, p=0.001; adult literacy ratio, p<0.001) and increasing proportion of those living on less than US$1 per day (p=0.011). These associations persist when haematological malignancies (known to have higher incidence in boys) are excluded from analysis. Despite substantial investment in poverty reduction and healthcare over the intervening decade—and considerable improvements in health indicators—the previously observed disparity in girls being registered with cancer remains in countries with poor health system indicators and low female education rates, particularly in populations that are poor. We suggest that girls continue to go unregistered or undiagnosed for cancer and that incidence data, particularly in developing countries, should continue to be interpreted with caution.