The purpose of this study was to explore how syntactic skill was maintained or lost by L2 Mandarin Chinese learners over time. In addition, this study endeavored to discover how a learner's L1 affects the attrition process of word order in Mandarin Chinese. To find out how certain Chinese syntactic structures were subject to attrition over time and how syntactic errors could be attributed to L1 transfer, five types of Chinese syntax that either resembled English, were very different from English, or had no counterpart in English were selected. They included subject-verb-object sentences, modifiers before modified, time and other adverbial clauses, and object-raising in Chinese specific ba construction. Twenty-four university students of Chinese-as-a-second-language speakers, who intensively learned and used Mandarin Chinese in a host culture setting for 16-22 months, participated in this study. By the time participants were tested a second time, they had discontinued regular usage of the L2 for 12 to 17 years. To find out how L2 syntactic attrition developed over time, participants were divided into three groups according to the year of departure from the L2 environment. They were also grouped into two groups by the length of time in the L2 setting to examine whether exposure time to the L2 affected the maintenance of overall L2 syntactic skill. The results indicated that the subjects retain a fair amount of their language education within the first couple years of discontinued regular L2 usage. In the meantime, it was found that the extra six months exposed to the L2 does not extend the long-term maintenance of overall L2 syntactic skill. The results did not show that the distance of structural properties between the learner's L1 and L2 necessarily predicted patterns of regression towards L1 syntactic ordering. Instead, the frequency of use, how often the structure appears in daily interaction with the target society and how well the syntactic structure was acquired in the first place, played a greater role in predicting whether the structure will likely be forgotten.