The Swedish Communicative Development Inventory (SECDI) is an important tool to assess infants’ productive vocabulary as reported by parents. The instructions SECDI gives to parents and their intuitive judgements naturally favour a strong semantic perspective. This study investigates the relationship between the reported productive vocabulary size and the phonological complexity of infant utterances. Productive vocabulary size was assessed in 17- to 18-month-olds (N=330) and in 20- to 21-month-olds (N=85). It is hypothesised that words with low phonological complexity are more frequently reported by parents and that phonological complexity will increase with infant age. Productive vocabulary size was measured from parental reports submitted via an online version of SECDI. To evaluate phonological complexity, only the part with single words was used – apart from 16 items consisting of lexicalised phrases, family names or multiple alternative utterances that were excluded. Phonological complexity was computed as the sum of the number of syllables (1 to 4), consonant clusters (0 to 4), and fricatives (0 to 3) occurring in each of the remaining 694 words. It ranged from 1 to 9 (low 1-3; high 7-9). Parents reported significantly more words with low phonological complexity. There is a significant interaction between the complexity level of the reported words and infant age. Words with more syllables, consonant clusters or fricatives were less frequent in the parental reports. This shows that data acquired with SECDI is not necessarily limited to a semantic perspective but can even provide information about phonological complexity.