The effects of floc properties (size and structure) on specific cake resistance and compressibility of cakes formed by dead-end MF were investigated. Hematite particles of primary size 70 run were flocculated in the presence of KCl and stirring and the resultant flocs were characterized in terms of floc size and fractal dimension. The results showed that larger flocs (ca 40 mum diameter) produced filter cakes of lower specific resistances and floc structural effects were more significant for smaller floc (ca 10 mum), with higher specific resistance for cakes formed from more compact flocs. These observations are explained by the balance of inter- and intra-floc flow and are in accord with a modified Carman-Kozeny relationship, which incorporates fractal dimension. Cake compressibility is strongly related to transmembrane pressure (TMP) particularly for smaller floc sizes. At low TMP (< 10 kPa) the estimated cake-averaged porosity is almost independent of floc size but at raised TMP (> 60 kPa) the porosity is strongly size dependent with higher porosities for larger floc. For the smaller flocs, cakes formed from the less compact floc (smaller fractal dimension) show greater tendency to compression.