OBJECTIVES: The objectives of this work are oriented in the first place to discuss the modalities of the financing of medicines, in special to study the characteristics of the access forms and financing to medicines according to the level of the income of the household in Mexico. In the industrialized countries the forms of financing of medicines, like the financing to the services of health is made by means of some scheme of copayment or subsidy the vulnerable groups. But in the non industrialized countries the main form of financing of medicines comes from the out-of-pocket household which is very inequitative. METHODS: For this study the registries of the surveys of households income by 2002 of Mexico to study the medicine expenditure by deciles of income. With this information the coefficients of Gini and the curve of Lorenz are considered. Additionally it is used the public and private information on the price and the cost in medicines. RESULTS: The access to medicines in Mexico is not related to the necessities of health but to the availability of income of the households, because 85 % of the medicines are acquired by means of the out-of-pocket money of households, because the social security provides free of charge medicines only 15 % of them. The income survey cost of the homes sample that 39 % of the medicine consumption in the private market both make last deciles of greater income; also one is that the consumption of the decil of greater income is four times superior to the one of the population with smaller income. CONCLUSION: The access to medicines in Mexico are not related to health needs but to household income. Also medicine prices constitutes an effective barrier to medicine acces to a suitable therapy.