The objective of this study was to assess socio-economic inequality in oral healthcare coverage among adults with expressed need living in 52 countries. Data on 60,332 adults aged 18 years or older were analyzed from 52 countries participating in the 2002-2004 World Health Survey. Oral healthcare coverage was defined as the proportion of individuals who received any medical care from a dentist or other oral health specialist during a period of 12 months prior to the survey, among those who expressed any mouth and/or teeth problems during that period. In addition to assessment of the coverage across wealth quintiles in each country, a wealth-based relative index of inequality was used to measure socio-economic inequality. The index was adjusted for sex, age, marital status, education, employment, overall health status, and urban/rural residence. Pro-rich inequality in oral healthcare coverage was observed within most of the countries, although lower income countries showed greater levels of relative inequality than higher income countries. Overall, lowest coverage and highest relative inequality were found in the low-income countries. The findings of this study may inform policies for oral health at global and national levels. To achieve universal coverage in oral healthcare, relevant interventions should reach the poorest population groups.