ABSTRACT The study was conducted to determine the feasibility for growing-out of the spotted babylon juveniles (Babylonia areolata) to marketable sizes with the large-scale operation of 20.0 x 20.0 x 1.5 m earthen ponds at Petchaburi province, Thailand. The production and economic analysis for monoculture of spotted Babylon were compared with the polyculture with sea bass (Lates calcarifer). Each pond was stocked with juveniles of 0.3 g initial weight at a density of 200 snails [m.sup.-2]. This study provides good results in growth and production of spotted babylon in earthen ponds. The average growth rates in body weight were 0.67 and 0.51 g [mo.sup.-1] for snails held in the monoculture and polyculture with sea bass, respectively. At the end of the experiment, total yield of spotted babylon held in the monoculture and polyculture with sea bass was 10,520 and 10,450 kg [ha.sup.-1], respectively. Based on farm data, stocking data and harvest data used in this study, total cost per production cycle of the monoculture and polyculture with sea bass were $19,184 and $23,245, respectively. The cost of producing spotted babylon marketable sizes in this grow-out farm design was $5.69 per kg and $6.95 per kg for the monoculture and polyculture trials, respectively. At a farm gate price in 2003 of $9.00 per kg resulted in a net return of $11,124 and $14,691 for the monoculture and polyculture with sea bass, respectively. The present study indicated the technically feasible, and economically attractive for monoculture and polyculture of B. areolata to marketable sizes in earthen ponds.