The applicability of Lacey's equations is tested for the river Brahmaputra. It is found that the river follows the structure of Lacey's regime equations. The perimeter and the area coefficients found in the modified regime equations are much higher than the corresponding coefficients in Lacey's original equations. Similarly, the velocity coefficient for the river Brahmaputra is considerably smaller than the coefficient in Lacey's corresponding velocity equation, whereas the coefficients of the equations for the hydraulic radius are of the same order. © 2008 International Association of Hydraulic Engineering and Research.