Purpose: To compare effectiveness of alternating current impedance spectroscopy technique (CarieScan PROTM) with tactile examination and bitewing radiography in detection of occlusal caries in primary teeth. Method: 110 primary molars in 40 patients aged 6 to 12 years were examined for presence of occlusal caries by tactile examination, bitewing radiography and CarieScan PROTMdevice. Results: Out of 110 teeth, 68 showed presence of dentinal caries and 42 showed presence of enamel caries. The highest sensitivity was seen with CarieScan PROTM (92.65%) followed by bitewing radiography (79.41%) and tactile examination (76.47%).95.24% specificity was seen with bitewing radiography, 92.86% specificity was seen with CarieScan PROTM followed by tactile examination with 71.43% which was least specific. Highest positive likelihood ratio was seen with bitewing radiography (16.68), followed by CarieScan PROTM (12.97) and tactile examination (2.68). Tactile examination (0.33) showedhighest negative likelihood ratio followed by bitewing radiography (0.22) and least with CarieScan PROTM (0.079). The diagnostic accuracy of CarieScan PROTM measurement was significant (AUC = 0.928, P < 0.001). Conclusions: In terms of sensitivity, likelihood ratios and accuracy, CarieScan PROTM performed better than tactile examination and bitewing radiography in early caries detection on non cavitated pits and fissures of primary teeth.