We performed a study on 96 patients to compare monitoring by immunoenzymologic measurement (EMIT) of digoxinemia. In doing so, we uniquely relied on clinical and electrocardiographic results. Compliance was good because only 9 patients had a digoxinemia equal or below 0.8 ng/ml, but we emphasize that our patients were hospitalized. Correlation between intoxications and plasmatic levels shows that 5 patients presented clinical or electrocardiographic signs indicative of digitalis intoxication with a digoxinemia less than 2.5 ng/ml and 14 patients without intoxication with a digoxinemia higher than 2.5 ng/ml. We point out in this study that for EMIT immunoassay it is better to take 2.5 ng/ml as the concentration limit to be sure to avoid intoxication.