In this study, itaconic acid (IA) was grafted on poly(vinyl alcohol) (PVA) at two different grafting percentages, 7.0% (w/w) and 14.0% (w/w), and membranes were prepared from the grafted copolymer (PVA-g-IA). Performances of PVA and PVA-g-IA membranes for the transdermal release of salicylic acid (SA) at in vitro conditions were investigated by using 2.0 mg/mL SA solutions. Effect of the pH on the release of SA was studied by keeping pH of donor and acceptor solutions in a range of (2.1-7.4). Permeation studies were also carried on at different SA concentrations. Effect of temperature on the release of SA was investigated in the temperature range of (32-39) (+/- 1)degrees C. Results showed that presence of IA decreased the release of SA from the PVA membranes and 73% SA was released at the end of 48 h at (32 +/- 1)degrees C from the IA-1 membranes. pH affected the release of SA through the grafted membranes and studies showed that release of SA was high with donor solution pH of 2.1. When the pH of donor and receiver solutions were kept at the same pH value, the overall SA% in permeate increased. Increase in concentration of SA decreased the release of SA for the studied membranes. Release of SA from PVA-g-IA membranes was temperature sensitive and increase in temperature from (32 +/- 1)degrees C to (39 +/- 1)degrees C increased the release percentage of SA by 24% (w/w). The overall activation energy for the permeation of SA through IA-I membrane was found to be 22.97 kJ/mol. (c) 2007 Wiley Periodicals, Inc.