In 179 samples of faeces from patients hospitalized with diarrhoeal diseases rotavirus infections were examined concurrently by three different sets--the latex agglutination test Diarlex Rota-Adeno (Orion Diagnostica) and two immunoenzyme tests (EIA)--EIA Rotavirus (Test-Line, CR) and IDEIA Rotavirus (Dako Ltd.) By the latex agglutination reaction the rotavirus infection was proved 31 times (17.3%), by the Test-Line test 87 times (48.6%), by the Dako test 96 times (53.6%). During the interval of 0-3 days after the onset of the disease the positivity assessed by different tests was 22.8%, 48.6% and 54.3%, on the 4th-7th day 12.8%, 51.1% and 57.4%, on the 8th and subsequent days 3.7%, 44.4% and 44.4%. Comparison of sets Orion Diagnostica and Dako revealed the sensitivity of the latex agglutination test only as 30.2% and specificity 97.6%. After the 9th day from the onset of the disease the infection was no longer confirmed by the latex agglutination test, while both EIA tests proved the rotavirus antigen up to the 16th day from the onset of the disease.