Children with specific language impairment (SLI) are often described as having great difficulty with grammatical morphology, but most studies have focused only on these children's use of verb morphology. In this study, we examined the use of noun phrase (NP) morphology by preschool-age children with SLI who are acquiring Swedish. Relative to typically developing same-age peers and younger peers matched according to mean length of utterance, the children with SLI had greater difficulty in the use of genitive inflections, indefinite articles, and article + adjective + noun constructions. Their difficulties were evidenced in omissions as well as substitutions. Furthermore, article omissions were more frequent in NPs containing an adjective and a noun than in NPs with only a noun. These findings indicate that in languages such as Swedish, NP morphology as well as verb morphology can be quite problematic for children with SLI. Factors that might have contributed to these children's difficulties are the lack of transparency of the gender of Swedish nouns, the morphological complexity of NPs containing adjectives in Swedish, the weak syllable status of articles, and the consonantal nature of some of the inflections.