Detection of the warning signals by the heart can be diagnosed from ECG.An accurate and reliable diagnosis of ECG is very important however which is cumbersome and at times ambiguous in time domain due to the presence of noise.Study of ECG in wavelet domain using both continuous Wavelet transform (CWT) and discrete Wavelet transform 100w products (DWT), with well known wavelet as well as a wavelet proposed better waters xl7000 by the authors for this investigation is found to be useful and yields fairly reliable results.In this study, Wavelet analysis of ECGs of Normal, Hypertensive, Diabetic and Cardiac are carried out.The salient feature of the study is that detection of P and T phases in wavelet domain is feasible which are otherwise feeble or absent in raw ECGs.