A simple and rapid, yet accurate, method for determination of serum iron (SI) and total iron-binding capacity (TIBC) is presented. The serum is first treated with sodium lauryl sulfate (SLS) to obtain a clear solution without deproteinization. This is followed by addition of acetate-SLS, hydroxylamine, and sulfonated bathophenathroline (SBP) as a single solution; these act as a buffer, a reducing agent, and a chromogen, respectively. The effect of temperature on color stability has been studied. Good recovery of iron added to serum, ranging from 96 to 100%, was obtained. Serial determinations with pooled sera yielded a range of 75 to 80 μg. per 100 ml., with a mean of 77.4 μg. per 100 ml. ± 1.3 SD, SE of the mean ± 0.24. Results of the method correlate well with results of the precipitation methods. The comparatively small serum samples utilized in this method make it suitable for routine pediatric analyses also.