Developmental model for small scale of poultry slaughterhouses in urban, Laksi district was conducted to study possible factors for pathogenic bacterial contamination on chicken carcasses and develop suggestions and comments to improve the small scale of poultry slaughterhouse by alleviating the pathogenic bacterial contamination. This study was performed during the mid of May 2012 to the mid of April 2013 at a poultry slaughterhouses in urban, Laksi district. The study consisted of 3 parts; 1) determining factors affecting pathogenic bacterial contamination on chicken carcasses in slaughtering process, 2) adjust working procedure and facilities of the slaughterhouse to reduce the contamination and 3) measure pathogenic bacterial contamination after improving the slaughterhouse. The total chickens included in the current study were 80 birds (40 birds for the 1st part and 40 birds for the 3rd part of this study). Collection of samples (swab and water) was classified into 3 processes; 1) before slaughtering process (pen floor, pen wall, live chickens and cloacal swab), 2) during slaughtering process (hands of staff in the slaughterhouse, killing knives, trimming knives, container for chickens after slaughtering, plucking machine, scalding water, water for washing after plucking, chicken carcass after plucking, water after evisceration and dressing table) and 3) after slaughtering process (chicken carcass ready to sell). All samples were analyzed for detecting Salmonella spp. and it’s serovar, and quantifying total aerobic plate count, E. coli and S. aureus in according to ISO 6579:2002, ISO 4833:2003, ISO 16649-2:2001 and ISO 6888-1:1999, respectively. The current study has demonstrated that the chickens had no harmful diseases for condemnation. The mian factors causing the contamination environment of the slaughterhouse (equipment, staff and live chicken) and micro-organisms in gastro intestinal tract of chickens. The adjustment for the slaughterhouse was focused on hygiene procedure with washing by water and chlorine solution for reducing the contamination, such as changing washing water after using, adjust work flow for evisceration department, chicken pen cleaning after use, cleaning equipment and dressing table & hand of the staff. The results have shown that: after the adjustment, 1) the prevalence of Salmonella spp. detection on final chicken carcasses was reduced significantly (from 70% to 2.5%), 2) the total aerobic counts concentration on the carcasses was depressed (from 8.16 × 103 CFU/cm2 to 2.46 × 103 CFU/cm2) and 3) the concentration of S. aureus on the carcasses was alleviated (from 75 CFU/cm2 to 55 CFU/cm2), although there was over accepted level of the recommendation of Thai Agricultural Commodity and Food Standard (TACFS) 6700-2005. In the meantime, there was no effect of the adjustment on concentration of E. coli on the final chicken carcasses, but the concentration level of E. coli was in the range of acceptation for the recommendation of the TACFS 6700- 2005. Therefore, strategies to reduce pathogenic microbial contamination in small scale of poultry slaughterhouses in urban, Laksi district should be focused on hygienic aspects by adjusting work procedure causing the microbial contamination with more attention paid for water washing, cleaning chicken pen and decontamination of equipment used in the slaughterhouse.