We previously demonstrated that intra-uterine growth-restricted (IUGR) Yucatan miniature pigs develop modestly elevated blood pressure (BP) as young adults. The present study evaluated the effects of a post-weaning Western-style, high-salt-fat-sugar (HSFS) diet on early programming of BP. IUGR piglets (3 d old, 0·77 (sem 0·04) kg, n 6) were paired with normal weight (NW) same-sex littermates (1·14 (sem 0·03) kg, n 6) and fed milk replacer for 4 weeks. A third littermate was left with the sow (SF; 1·01 (sem 0·05) kg, n 6). When 4 weeks old, all pigs were placed on a HSFS diet ad libitum for 5 h/d. When 11 months old, telemeters were implanted to measure BP in pigs before (4·5% NaCl) and after (0·5% NaCl) a 7 d reduced salt challenge. At necropsy, nephron numbers were determined. Before sexual maturity, IUGR pigs had greater relative feed intake (P<0·05), and experienced catch-up growth with greater adiposity, with correlations between adiposity and BP (P<0·05). Adult IUGR pigs had 26-34% fewer nephrons and higher diastolic BP (107·7 (sem 4·9) mmHg, P = 0·044) than NW (97·2 (sem 1·8) mmHg) and SF (98·9 (sem 5·3) mmHg) pigs. Systolic BP was similar among the three groups, but was significantly elevated compared with levels previously reported for a control diet. Salt restriction reduced BP in all groups (P<0·05), but with no differences (P>0·05) in the degree of salt sensitivity among groups. In conclusion, a post-weaning Western-style diet exacerbates early programming of diastolic BP in Yucatan miniature swine, whereas systolic BP is more sensitive to postnatal diet.