The publishers of Physiological Measurement (PMEA), IOP Publishing, in association with the journal owners, the Institute of Physics and Engineering in Medicine (IPEM), jointly award an annual prize for the best paper published in PMEA during the previous year. The responsibility for deciding the ultimate winner falls to the Editorial and International Advisory boards of the journal. However, a shortlist of papers has to first be put together. Since a paper published early in the volume will have more exposure than one published later, it would be unfair to use download or citation statistics to judge papers. For this reason, the shortlist is constructed using the comments and ratings of our expert referees. For the 2009 award, 6 papers were considered. After the construction of the shortlist, it was then down to our board members to personally assess and rank the papers. This year, we have a clear and worthy winner. We have much pleasure in advising readers that the 2009 Martin Black award goes to Andy Adler et al for their paper on electrical impedance tomography. GREIT: a unified approach to 2D linear EIT reconstruction of lung images Andy Adler, John Arnold, Richard Bayford, Andrea Borsic, Brian Brown, Paul Dixon, Theo Faes, Inez Frerichs, Herve Gagnon, Yvo Garber, Bartlomiej Grychtol, Gunter Hahn, William Lionheart, Anjum Malik, Robert P Patterson, Janet Stocks, Andrew Tizzard, Norbert Weiler and Gerhard K Wolf 2009 Physiol. Meas. 30 S35-55 All of the shortlisted papers were of great merit, and the full top-6 is listed below (in alphabetical order). Richard Bayford Editor-in-Chief Jon Ruffle Publisher References Adler A, Arnold J H, Bayford R, Borsic A, Brown B, Dixon P, Faes T J C, Frerichs I, Gagnon H, Garber Y, Grychtol B, Hahn G, Lionheart W R B, Malik A, Patterson R P, Stocks J, Tizzard A, Weiler N and Wolf G K 2009 GREIT: a unified approach to 2D linear EIT reconstruction of lung images Physiol. Meas. 30 S35-55 Aelen P, Jurkov A, Aulanier A and Mintchev M P 2009 Pilot acute study of feedback-controlled retrograde peristalsis invoked by neural gastric electrical stimulation Physiol. Meas. 30 309-22 Borsic A, Halter R, Wan Y, Hartov A and Paulsen K D 2009 Sensitivity study and optimization of a 3D electric impedance tomography prostate probe Physiol. Meas. 30 S1-18 Kim K K, Kim J S, Lim Y G and Park K S 2009 The effect of missing RR-interval data on heart rate variability analysis in the frequency domain Physiol. Meas. 30 1039-50 Remme E W, Hoff L, Halvorsen P S, Naerum E, Skulstad H, Fleischer L A, Elle O J and Fosse E 2009 Validation of cardiac accelerometer sensor measurements Physiol. Meas. 30 1429-44 Wang L, Su S W, Celler B G, Chan G S H, Cheng T M and Savkin A V 2009 Assessing the human cardiovascular response to moderate exercise: feature extraction by support vector regression Physiol. Meas. 30 227-44 [ABSTRACT FROM AUTHOR]