The External Quality Control Program of the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC) includes controls for bacteriology, serology, mycology, parasitology, mycobacteria, virology and molecular microbiology. This article presents the most important conclusions and lessons drawn from the 2007 controls. As a whole, the results obtained in 2007 confirm the excellent skill and good technical standards found in previous years. However, erroneous results can be obtained in any laboratory and in clinically relevant determinations. A few deviations were observed in some controls, calling for critical reflection. Once again, the results of this program highlighted the need to complement internal with external controls, such as those offered by the SEIMC program.