This study was to know the effects of abattoir, chlorinated antimicrobial intervention and brining on microbiology of post 6 months' frozen (-10±2 °C) and thawed mixed chicken portions, as well as determine the optimal brining levels. Broilers (5-6 weeks old, n = 180, 1.12-1.25kg carcass weight) processed at 3 different processing plants (n = 60 per abattoir) into chicken portions of breasts, thighs and wings were packaged in 1 kg bags after applying antimicrobial intervention and brining before quick freezing them. After 6 months quick freezing at -10 °C and thawing, standard plate counts (SPC), spore counts and psychrophilic counts (log cfu/g) were evaluated and subjected to ANOVA in a randomized complete block design (RCBD). No coliforms, molds, staphylococci, and yeasts were not detected due to abattoir, antimicrobial and brining interventions. Also no significant SPC, spore count and psychrophilic bacterial count (P > 0.05) effects was recorded due to abattoirs. ASC significantly (P < 0.05) lowered all the counts compared to Aq. Cl and ClO2. The 0% brine had highest (P < 0.05) counts (3.33, 3.25 and 3.63 logCFU/g) for SPC, spores and psychrophilic bacteria respectively, while 30 and 35% levels had the least (P < 0.05) counts (ranges from 1.06 -1.87 logCFU/g) per sample tested with no significant interaction effects recorded. There is a significant optimal brining levels of 13.27, 35.87 and 34.10 (%) for SPC, spores and psychrophilic counts based on the quadratic regression model.