Ln2Ru3Al15 (Ln = Ce, Gd) have been synthesized, and the competition between the growth of Ce2Ru3Al15 and CeRu2Al10 has been studied. The structure of Ce2Ru3Al15 was modified from the previously reported Ce2Ru3Al15 structure, and the structure of Gd2Ru3Al15 was determined for the first time. The magnetic and transport properties of Ln2Ru3Al15 were measured and compared to the properties of LnRu2Al10. Gd2Ru3Al15 orders antiferromagnetically at 21.0 K with a spin reorientation at 4.1 K and has a positive paramagnetic Curie-Weiss temperature of 11.5(17) K, suggesting strong ferromagnetic interactions within the structure. Ce2Ru3Al15 displays two low-temperature magnetic transitions at 3.7 and 3.1 K, the first of which is believed to be an antiferromagnetic ordering, with a θN of -7(3) K and a reduced moment of 2.33(4) μB/mol-Ce. Furthermore, the low-temperature magnetic and transport properties display the effects of Kondo screening of the magnetic moments. While structurally related, the properties of Ce2Ru3Al15 do not display the same anomalous features observed in CeRu2Al10.