The full-information maximum likelihood (FIML) method makes it possible to estimate and analyze structural equation models (SEM) even when data are partially missing, enabling incomplete data to contribute to model estimation. The cornerstone of FIML is the missing-at-random (MAR) assumption. In (unidimensional) computerized adaptive testing (CAT), unselected items (i.e., responses that are not observed) remain at random even though selected items (i.e., responses that are observed) have been associated with a test taker's latent trait that is being measured. In multidimensional adaptive testing (MAT), however, the missingness in the response data partially depends on the unobserved data because items are selected based on various types of information including the covariance among latent traits. This eventually may lead to violations of MAR. This study aimed to evaluate the potential impact such a violation of MAR in MAT could have on FIML estimation performance. The results showed an increase in estimation errors in item parameter estimation when the MAT response data were used, and differences in the level of the impact depending on how items loaded on multiple latent traits.