The possibility of detecting very small defects in concrete was presented, representing disbands, voids and inhomogeneities, using the thermal imaging technique. Results are compared with pulse travel times measured using the ultrasonic pulse velocity (USPV) technique. Two types of specimens were prepared, beams and slabs, using grade 43 cement, Zone II sand as per IS 383 and 10-mm crushed coarse aggregate. The USPV and the thermal imaging techniques were applied on the four specimens to study the variations introduced by the experimental defects. A thermal image of the slab which had wooden blocks embedded at different depths can easily identify the region of discontinuity at depths of 10, 20, 30 and 40 mm. It is found that as compared to the conventional techniques, the thermal imaging provides an easy to interpret visual picture, in a single scan of the specimen used.