The objective of this research was to know the difference between the penetration of glass ionomer cement (Chemflex, Dentsply) in dentin of primary teeth with and without conditioner (10% polyacrylate acid). The primary molar tooth which were observed by Scanning Electron Microscopy (SEM). 1000X magnitude was measured for the length of glass ionomer cement penetration in dentin of primary tooth with and without conditioner. The t test showed that there was no significant difference between the length of glass ionomer cement penetration in dentin of primary teeth with and without conditioner (t=1,78; p>0,05).