To test whether low doses of the NMDA-receptor partial-agonist D-cycloserine would enhance intermittent TBS (iTBS) treatment outcomes in MDD, this single-site 4-week, double-blind, placebo-controlled, randomized clinical trial compared TBS with D-cycloserine vs. TBS with placebo. The TBS plus D-cycloserine group had greater improvements in MADRS scores compared with the iTBS plus placebo group, with a mean difference of −6.15.