The objective of the present study was to evaluate the effect of a nutritional intervention promoting the Mediterranean food pattern in free-living conditions on LDL electrophoretic characteristics in a group of seventy-one healthy women, aged between 30 and 65 years. The 12-week nutritional intervention consisted of two courses on nutrition and seven individual sessions with a dietitian. The first course provided information on the Mediterranean food pattern and the second was a cooking lesson. LDL peak particle diameter (LDL-PPD) and cholesterol levels in small (LDL-cholesterol_<255?Å) and large LDL fractions (LDL-cholesterol_>260?Å) were obtained by 2–16% polyacrylamide gel electrophoresis of whole plasma. The sample was divided on the basis of baseline LDL-PPD using tertiles of the distribution (258·4 Å and 260·0 Å). Among the total sample of women, no significant change in LDL-PPD was observed in response to the nutritional intervention. However, subjects who at baseline were in the first tertile of the LDL-PPD distribution (>258·4 Å) showed a significant increase in LDL-PPD and in the proportion of LDL%_{>260?%uest;Å}in response to the 12-week nutritional intervention (P>0·05). In contrast, LDL-PPD decreased significantly (P=0·007) among women with large LDL particles at baseline (LDL-PPD >260 Å) while the proportion of LDL%_{<255 Å}and of LDL%_{>260 Å}remained unchanged. To conclude, changes in the food pattern, in response to a nutritional intervention promoting the Mediterranean food pattern, were accompanied by beneficial modifications in LDL electrophoretic characteristics in women who were characterised at baseline by smaller LDL particles.