The present invention relates to a method for the in-ovo sex identification of chicks, comprising the following steps: extracting a sample solution of allantoic fluid from an egg; uniting the sample solution extracted from the egg with an oestrone-derivative-specific antibody and a conjugate solution with a conjugate binding to the antibody; and identifying the oestrone derivative concentration of the extracted allantoic fluid by means of the conjugate bound to the antibody. In order to accelerate the identification of the oestrone derivative concentration the oestrone-derivative-specific antibody is surface-bound.
