The present opinion deals with the assessment of the data provided by interested business operators in support of an amendment of the EU speciﬁcations for titanium dioxide (E 171) with respect to the inclusion of additional parameters related to its particle size distribution. Titanium dioxide which is used as a food additive E 171 in food undergoes no surface treatment and is not coated. It consists of anatase or rutile generally containing small amounts of the other phase (rutile or anatase, < 2% m/m) and it may also contain small quantities (< 0.5%) of constituent particle growth and crystal phase control agents (alumina, sodium or potassium in combination with phosphate). Particle size analyses, by TEM, SEM, XDC or DC, have been carried out on ﬁve commercial brands of anatase E 171 and one of rutile E 171 manufactured by the only three EU manufacturers that, according to information submitted by interested business operators, produce food-grade titanium dioxide. Interested business operators proposed to introduce in the EU speciﬁcations for E 171 a speciﬁcation of more than 100 nm for median Feret min diameter and less than 50% of the number of constituent particles below 100 nm; measured by EM in both cases. The Panel, after reviewing the data, concluded that a speciﬁcation of more than 100 nm for median minimal external dimension, equivalent to less than 50% of the number of constituent particles with a median minimal external dimension below 100 nm, should be inserted in the current EU speciﬁcations. The Panel considered that the conclusions made, and the uncertainties identiﬁed, in the previous EFSA assessments on E 171 remain valid. The Panel reiterates the need for the further research as recommended in the previous opinions in order to decrease the level of uncertainty and acknowledged that additional studies with characterised E 171 are being carried out by interested business operators.