Abstract: Isonicotinic acid hydrazide as a reagent for the spectrophotometric determination of △⁴-3-ketosteroid hormones based on the formation of their hydrazones in acid-alcohol solution has been reported by Umberger. The method was applied to the analysis of vegetable oil solution of testosterone propionate and progesterone. It was pointed out to be suitable for the estimation of other △⁴-3-ketosteroids, such as methyl-testosterone cortisone, hydrocortisone, and desoxycorticorterone. However, no mention of further application to the △^1,4-3-ketosteroid hormones was made. We found that prednisone and prednisolone can also react with isonicotinic acid hydrazide to give yellow solutions having an absorption maximum at 400—402 mμ. The conditions for the colorimetric determination of these two hormones were studied and the method was applied to the analysis of their tablets. Furthermore, by varying the concentration of hydrochloric acid and isonicotinic acid bydrazide of Umberger's procedure, the above mentioned △⁴-3-ketosteroid hormones and their preparations can be determined colorimetrically. The results obtained by the proposed method both for six △⁴-3-ketosteroid and two △^1,4-3-ketosteroid hormones were found in close agreement with those of the official methods in U.S.P. ⅩⅥ and B.P. 1958. As a result of this study, a simple and accurate method has been proposed for the colorimetric determination of eight steroid hormones and most of their preparations by using the same reagent.