Seizure-related gene 6 (sez-6) is a trans-membrane protein expressed by neuronal cells that modulates dendritic branching. It has three clusters of eleven possible N-glycosylation sites in the extracellular domain region: sugar chain (SC)1-3， SC4-7， and SC8-11. Recent reports suggest that N-glycosylation modulates the membrane trafficking and function of trans-membrane proteins. Here， we studied the role of N-glycosylation in sez-6 function. We transfected mutants lacking one， two， or all N-glycosylation clusters into neuro2a cells. A mutant lacking all N-glycosylation was transported to the cell membrane. Mutants lacking one cluster (sez-6 ΔSC1-3， ΔSC4-7， ΔSC8-11) were evenly distributed on the cell membrane and secreted into the conditioned medium， as in wild-type sez-6; in contrast， the unglycosylated mutant， sez-6 ΔSC1-11， and mutants having only one cluster (sez-6 SC1-3， SC8-11) were localized in some portions on the cell membrane. Despite sez-6 SC4-7 having only one cluster， it was transported like the wild type. Among mutants behaving like the wild type， sez-6 ΔSC1-3 and ΔSC4-7 reduced neurite formation. Interestingly， mutants lacking SC4-7 (sez-6 ΔSC4-7) did not affect the formation of filopodia-like protrusions. In contrast， other mutants as well as the wild type induced it， suggesting that SC4-7 is crucial for filopodia-like protrusions. Our results indicate that N-glycosylation regulates cell morphology through modulating the cell surface distribution of sez-6 protein.