The existing procedures for estimating short-term deflections, in prevailing codes, are based on empirical formulations of the effective moment-curvature relation. A comparison of codes shows considerable disparities in the prediction of the cracking moment, moment-curvature and load-deflection behaviour. Experimental studies on six one-way slab specimens reveal that, among the various methods, Euro code 2 method of calculating the cracking moment shows good agreement with the test results, whereas ACI 318 method of calculating deflections shows a load-deflection behaviour trend that is closest to the experimental curve, but with a higher slope. Based on the experimental results, an improved procedure is proposed, which adopts the Euro code 2 cracking moment formula combined with a modified ACI 318 code formula.