Last year Lancet published a series of articles on Mexico's 2004 health system reform. This article reviews the reform and its presentation in the Lancet series. The author sees the 2004 reform as a continuation of those initiated in 1995 at the largest public social security institute and in 1996 at the Ministry of Health, following the same conceptual design: "managed competition". The cornerstone of the 2004 reform-the voluntary Popular Health Insurance (PHI)--will not resolve the problems of the public health care system. The author assesses the robustness and validity of the evidence on which the 2004 reform is based, noting some inconsistencies and methodological errors in the data analysis and in the construction of the "effective coverage" index. Finally, some predictions about the future of PHI are outlined, given its intrinsic weaknesses. The next two or three years are critical for the viability of PHI: both families and states will face increasing difficulties in paying the insurance premium; health infrastructure and staff are insufficient to guarantee the health package services; and the private service contracting will further strain state health ministries' ability to strengthen service supply. Moreover, redistribution of federal health expenditure favoring PHI at the cost of the Social Security Institute will further endanger public health care delivery.