In this study, segmentation of frontal breast tissues in infrared thermography is proposed using modified phase based level set method. The images considered for this work are obtained from open source database PROENG. An improved diffusion rate model is adopted and incorporated in distance regularized level set framework. Local phase information is used as an edge indicator for the evolution of level set function. Region based statistics and overlap measures are computed to compare and validate the segmented region of interests against ground truths. Further, the obtained values are compared with the reported numerical values of three segmentation methods. The results show that the proposed level set method is able to extract the breast tissues in infrared images and able to address the inherent limitations in thermograms such as low contrast and absence of clear edges. A high amount of correlation between the segmented output and ground truths is observed. The performance of the proposed segmentation method is better when compared to reported segmentation methods. The adopted method seems to be effective in identifying the lower breast boundary and inflammatory folds present in breast thermograms. © Springer-Verlag Berlin Heidelberg 2014.