Phonotactic patterns of seven 11-15-year-old Kannada speaking children with Down syndrome (DS), mental age matched children with mental retardation (MR) without DS and six 4-5-year-old typically developing (TD) children were investigated. Conversational speech analyses and target analyses of conversational speech were carried out in all three groups of participants. Imitated speech samples from both groups of children with disorders were also analysed with respect to phonotactic patterns. Both conversational and imitated speech analyses revealed that children with DS showed a higher percentage of occurrences of simpler phonotactic patterns than the later acquired complex ones. Target analyses revealed certain similarities in all three groups indicating that while persons with Down syndrome attempted certain complex phonotactic shapes, errors such as consonant deletions, syllable deletions and cluster reductions led to the use of simpler phonotactic patterns. Based on these analyses, the study explores the possible presence of Childhood Apraxia of Speech (CAS) in children with DS and stresses the importance of assessing phonotactic deficits in these children. (Contains 6 figures and 4 tables.)