Comorbidity of motor and speech/language impairments was investigated in 363 preschool children between the ages of 5 and 6 years (boys: 205, age 6.04±0.48 years; girls: 158, age 5.98±0.53 years). The children were sampled from two municipals of Taiwan, and were determined to present no apparent neurological, musculoskeletal, cardiopulmonary system impairment or mental insufficiency. They were administered with three speech/language tests and a motor test (Movement Assessment Battery for Children, or M-ABC). The results showed a significant correlation between the total score of the motor test and the total score of each of the speech and language tests. Regression analysis that controlled for IQ (C-TONI) further showed that manual dexterity, but not ball skills or balance, of M-ABC was predictive of all scores on the speech and language tests. To determine a deficit on a test, a score at or below the 10th percentile of the norm or a score at or below 1.25SD from the group mean was established as the cutoff. For the speech/language impairment, a deficit on at least two out of the three tests also applied. Following these criteria, 22 children (6.1%) were identified to have Developmental Speech and Language Disorder (DSLD), and 45 (12.4%) to have Developmental Coordination Disorder (DCD). Comorbid DSLD and DCD were found in six children (1.65%). Chi-square analysis revealed a significant correlation between DSLD and DCD (p <.03). The odds of DSLD was higher (by about three-fold) among the children with DCD than among the children without (0.15 vs. 0.05). Comorbid motor and speech/language impairments in preschool children appear to be a significant clinical condition that requires the attention of the therapeutic community. Manual dexterity, in particular, seems to be an important clue for understanding the shared mechanism of motor and speech/language impairments.