An early and accurate diagnosis of multiple sclerosis (MS) is very important, since it allows early treatment initiation, which reduces the activity of the disease. Oligoclonal IgG band (OCGB) detection is a good ancillary tool for MS diagnosis. However, it was argued that its usefulness was limited by the high interlaboratory variability. In the last years, different techniques for OCGB detection have appeared. We performed a blinded aleatorized multicenter study in 19 Spanish hospitals to assess the accuracy and reproducibility of OCGB detection in this new scenario. We studied cerebrospinal fluid (CSF) and serum samples from 114 neurological patients. Every hospital contributed to the study with triplicated pairs of CSF and serum samples of six patients and analyzed 18 different samples. Global analysis rendered a sensitivity of 92.1%, a specificity of 95.1% and a Kappa value of 0.81. This shows that current techniques for OCGB detection have good accuracy and a high interlaboratory reproducibility and thus, represent a good tool for MS diagnosis. When we analyzed separately the different techniques used for OCGB detection, the highest concordance was observed in western blot with alkaline phosphatase detection (kappa=0.91). This indicates that high sensitivity techniques improve the reproducibility of this assay.