Under the assumptions of the continuous distribution and equality of variance, we consider multiple comparisons tests for the differences among mean responses in k samples. Closed testing procedures are superior to the Tukey-Kramar type multiple tests which are single-step procedures in many cases. The closed testing procedure more powerful than the Tukey-Welsch test and the REGW test is proposed under the usual normality. Furthermore the nonparametric closed testing procedure is discussed based on ranks. Last the proposed nonparametric closed testing procedure is illustrated with data regarding sarcoidosis from the assay of serum angiotensin-converting enzyme (SACE).