Antecedentes: durante el 2005 y 2006, Colombia adelanto una Jornada Nacional de Vacunacion contra sarampion y rubeola, en la cual fue posible prever que algunas gestantes recibirian la vacuna de forma inadvertida y, para evitar su implicacion de forma negativa en el producto del embarazo, se establecio para su seguimiento la vigilancia epidemiologica. Metodos: se realizo un estudio descriptivo de mujeres entre 14-39 anos vacunadas contra la rubeola y el sarampion que desconocian estar embarazadas en el momento de recibir la vacuna. Se aplicaron pruebas detectoras de inmunoglobulina M (IgM) e inmunoglobulina G (IgG) contra el virus de la rubeola, clasificandolas como inmunes si se obtenian resultados negativos a IgM y positivos a IgG, en un lapso no mayor de 30 dias despues de la vacunacion; se definieron como susceptibles si se obtenia un resultado positivo a IgM despues de la vacunacion, o indefinido si se obtenian resultados negativos a IgM y positivos a IgG tras un intervalo mayor de 30 dias entre la vacunacion y la aplicacion de las pruebas serologicas. Resultados: de 3489 gestantes vacunadas, 2732 obtuvieron un resultado de IgM (-) (78,3%); 510 fueron positivas para IgG-inmunes, y 87 negativos- susceptibles-; por IgM (+) se definieron como susceptibles 277 (7,9%) del total de casos. Es decir, se identificaron 364 (10,4%) casos susceptibles, 510 inmunes (14,6%), 66 (1,8%) con un resultado dudoso o sin segunda muestra y, 414 (11,8%) no se obtuvieron muestras por laboratorio. La seropositividad a IgM segun el intervalo entre la vacunacion y la aplicacion de las pruebas serologicas fue de 5,4% (0-30 dias; 10,1% (31-60 dias); 8,4% (61-90 dias), y 8,5% (≥ 90 dias). En cuanto a la edad, se encontro que el grupo de 16-25 anos tenia la mayor proporcion de personas susceptibles a la rubeola (6,6%) y representaba el 46.9%(130/277) de todas las mujeres susceptibles Conclusione se justifico la vacunacion poblacional de todas las mujeres en edades entre los 14-39 anos sobre la base de datos epidemiologicos y serologicos. Durante el seguimiento de las embarazadas no se observo ningun caso de sindrome de rubeola congenita ocasionado por la vacuna antirrubeolica. Abstract Antecedents: during 2005 and 2006 Colombia implemented a nationwide day of vaccinations against Measles and Rubella, in the event it was to be expected that some pregnant women would be inadvertently administered with the vaccine. In order to prevent any detrimental effects on the pregnancy, these women were subsequently monitored by means of an epidemiological study. Methods: a field study was conducted into women aged between 14 and 39 who had received the Rubella and Measles vaccine without knowing that they were pregnant. Immunoglobulin M (IgM) and immunoglobulin G (IgG) tests for the detection of the rubella virus were applied in each case. If, within a period of no greater than 30 days from the moment of vaccination, the IgM results proved negative and the IgG results positive then the women were declared immune. However if the IgM results taken immediately after the vaccination registered as positive then the women were categorised as susceptible to the virus. The woman were classified as indeterminate if they showed negative IgM results and positive IgG results in a period exceeding the 30 days lapse between the vaccination and the application of the serological tests. Results: among 3,489 pregnant women that were administered with the vaccine, 2,732 displayed IgM results of (-) (78.3%); 510 displayed positive indices in the IgG – immunity tests, and 87 were negative-susceptible in this case-; out of all the cases treated in the IgM (+) band 277 (7.9%) were classed as susceptible. This is to say that 364 (10.4%) cases were identified as susceptible whilst 510 (14.6%) were deemed immune and only 66 (1.8%) appeared as doubtful or without result on second trial. 414 (11.8%) did not obtain their results in a laboratory. Those who proved HIV positive in reaction to the IgM - results are specific to the time lapse between the date of vaccination and the application of the serological tests – were as follows: 5.4%(0-30 days); 10.1% (31-60 days); 8.4% (61-90 days), and 8.5% ((≥ 90 days). With regards to the age of the patients, of the total number or women considered susceptible, it was discovered that the group aged between 16 and 25 years which represents 46.9% (130/277) were more susceptible (6.6%) to rubella. Conclusions: the serological and epidemiological data collected warranted the cross – sector application of the vaccine to women between the ages of 14 – 39 years. None of the pregnant women subsequently monitored displayed signs of congenital rubella syndrome that could have been the result of the preventative rubella vaccine. Keywords: epidemiological controls, rubella, vaccination.