This present research aims to study the relative sexual size dimorphism of Centrobolus (Cook) in 18 congenerics. Millipedes illustrated reversed sexual size dimorphism (SSD) where females were larger than males; and broke Rensch's rule as this dimorphism increased with body size. SSD was calculated in 18 species of the genus Centrobolus and illustrated was regressions; male versus female SSD and SSD vs body size. An allometric equation for Centrobolus was (1) ?=0.00051x-0.01071. SSD ranged from 0.63-2.89 (1.55±0.63; n not less than 18) and was not negatively correlated (R=0.70485; P=0.00109; n=18 spp.) with volume ranging from 284-2683 mm3 (1097.89±638.06; 18). The rejection of the rule appears consistent among arthropods.