The effects of in vitro culture methods on morphological development and infectivity of Strongyloides venezuelensis filariform larvae ($L_3$) to rats were investigated. A significantly higher body length was observed in $L_3$ from filter paper culture ($597.3{;}{pm}{;}32.2{;}{mu extrm{m}}$) than those in fecal (($509.9{;}{pm}{;}35.0{;}{mu extrm{m}}$) and nutrient broth culture (503.3{;}{pm}{;}31.0{;}{mu extrm{m}}) (P<0.05). Larval infectivity was assessed by exposing rats to 1,000 $L_3$ from each culture and worms were recovered from the lungs and small intestines. Recovery rate of these worms did not show any significant difference. A significantly greater body length of adults was recorded in those corresponding to the $L_3$ harvested from filter paper (2,777.5{;}{pm}{;}204.4{;}{mu extrm{m}}$</TEX>) and nutrient broth culture (($2.732.5{;}{pm}{;}169.8{;}{mu extrm{m}}$) than those corresponding to the $L_3$ obtained from fecal culture (($2.600.5{;}{pm}{;}172.4{;}{mu extrm{m}}$) (P<0.05). Although worm fecundity and EPG counts differed among culture methods but worm burdens and course of infection did not. These findings suggest that the methods of cultures have a significant effect on the morphological development of the larvae to the $L_3$ stage, but do not influence the infectivity to rats.