In order to identify initial factors that can affect shrimp postlarvae survival during larval rearing, three larval rearing facilities from the Caribbean coast of Colombia were sampled for 71 nauplii batches during 10 months of 1996. For each batch, qualitative variables (origin, transportation mode, presence of bacteria in transport water) and quantitative variables (transportation time and density, physicochemical parameters of the water, proportion of each nauplii stage and of deformed nauplii) were monitored. Water quality and density (nauplii/l) variables were monitored during the whole process of nauplii packing, transport, reception, acclimatization and stocking. To evaluate the relationship between qualitative variables and larval rearing survival, a multiple factor variance analysis was run, while, for quantitative variables, a stepwise multiple regression model was developed. Variables with significative (P<0.05) influence on larval rearing survival were the transportation mode (with small private aircraft, average survival was 45%, compared to 35% with a pressurized commercial aircraft), the presence of bacteria (growing on T.C.B.S. media) in nauplii transport water (survival without these bacteria in water was 59% compared with 40% when these bacteria were observed) and the percentage of deformed nauplii. Furthermore, the specific presence of bacteria like Vibrio metschnikovii, Flavobacterium spp. and Alcaligenes spp. in nauplii transport water was a worsing factor.