Gastroserica contaminata is a species of beetle of the family Scarabaeidae. It is found in Laos.
Adults reach a length of about 7.3 mm. They have an oval body. The ventral surface, labroclypeus, legs, elytra and lateral margins as well as a median stripe of the pronotum are all yellow, while the frons, elytral margins as well as spots on the intervals, and on the pronotal disc are dark brown, sometimes with a metallic-green shine. The dorsal surface is dull, with moderately dense erect setae mixed with dense and short ones.
The species name is derived from Latin contaminatus (meaning spotted).