Objective: To determine the sulcus penetration ability of hydrophilic and hydrophobic polyvinyl siloxane (PVS) impression materials by impression technique, temperature, and sulcus width. Method and Materials: Hydrophilic Flexitime (FLE; Heraeus Kulzer) and its hydrophobic counterpart (EXP) without surfactant were investigated, using light (L), monophase (M), and heavy (H) consistencies. A truncated steel cone surrounded by a 2-mm–deep and 50-, 100-, or 200-µm–wide sulcus, simulating the gingival tissue with agar, served as the test model. Impressions were made with single-mix (L or M) and double-mix (LM or LH) techniques at 23°C and 37°C, respectively. The reproduced sulcus heights were measured with a 3D laser scanner. Data were analyzed by ANOVA and Tukey HSD (P < .05). Results: Irrespective of sulcus widths and temperature FLE-L penetrated deepest (> 1.9 mm); FLE-M, -LM, and-LH reproductions were shorter with narrow sulci. Repro­ductions of 50- and 100-µm sulci with EXP-L were shallower than with FLE-L. The shortest reproduction was, however, greater than 1.6 mm. Conclusions: In spite of some significant differences found in sulcus-reproducing ability with hydrophilic and hydrophobic impression materials applied at different impression-making temperatures and with different techniques, the practical relevance is limited. (Quintessence Int 2010;41:e43–e50)