A study of attenuation of seismic refraction waves in sedimentary layers is carried out at two sites near Al-Riyadh and Baiji towns, Kirkuk Governorate in order to determine the attenuation coefficients of the two sites. The distance between these two sites is about 40 Km. Calculation of attenuation coefficients is based upon analysis of seismic field records, which are consist measurements using both vertical and horizontal geophones.The geometrical spreading factors for both longitudinal ( np) and transverse (ns) waves and their attenuation coefficients (αp, αs) are determined from the seismic data. The predominant frequency (fp,fs) with the quality factors (Qp,Qs) for both waves are also determined. The calculated values for np, ns, αp, αs, fp, fs, Qp, Qs and αs/αp at the first site are 2.106, 1.66, 0.057, 0.073, 55, 30.2, 7.2, 2.8 and 1.5 respectively. For the second site, only longitudinal wave is used to calculate the attenuation coefficient αp, predominant frequency (fp) and quality factor(Qp). The obtained values for np, ap, fp and Qp are 2.21, 0.055, 51 and 3.6 respectively.The obtained values can be considered as representative to the sedimentary layers in this area and can be of useful applications.