<i>Background:</i> Short small-for-gestational-age (SGA) children experience pre- and postnatal growth restriction, which might be influenced by polymorphisms in the <i>IGF1</i> gene. The well-known –841(CA)_n/192 bp polymorphism has been associated with birth size and cardiovascular disease. <i>Aims:</i> To determine whether birth size, postnatal growth and growth during growth hormone (GH) treatment, were associated with <i>IGF1</i> gene polymorphisms and haplotypes. <i>Methods:</i> 201 short SGA children were investigated for four <i>IGF1</i> gene polymorphisms in the promoter (–G1245A, –841(CA)_n), intron 2 (+3703(CT)_n) and 3UTR (+A1830G). Spontaneous growth and growth during GH treatment were studied. <i>Results:</i> The –1245 A allele was identified as a marker-allele for the well-known –841(CA)_n/non-192 bp allele, both part of haplotype 2. The –1245 A allele was not associated with head circumference at birth, but was associated with a postnatal 0.3 SDS smaller head circumference at age 1–3. The –1245 A allele was also associated with a 1-week shorter gestational age which explained the association with a smaller absolute birth size. No associations were found with gestational age-adjusted birth size, height and weight SDS during postnatal life and with growth during GH treatment. <i>Conclusions:</i> The –G1245A SNP appeared to be a marker for the well-known –841(CA)_n/192 bp polymorphism. Haplotype 2, of which the –1245 A allele was the marker, was associated with a smaller head circumference SDS during spontaneous postnatal growth, but not during GH treatment.