The advantages of multivariate calibration by using more than one selective emission line for one analyte are described in comparison with univariate calibration. Principle component regression (PCR) and partial least squares regression (PLS) are compared with classical univariate linear regression of single lines. Practical applications in spark- and inductively coupled plasma optical emission spectroscopy (ICP-OES) show that the sensitivity can be increased and thus a lower limit of detection be obtained by means of these multivariate techniques. Results from the investigations concerning the problem of collinearity are also discussed. Disturbed analyte lines are included in multisignal calibration. Their influence on the results of calibration is described.