Abstract: The experiment on effect of different diets on various biological parameters conducted at Karachi Sindh, Pakistan revealed that the German cockroach, B. germanica was reared at constant temperature of 31±2°C under laboratory conditions with supply of three diets and water. The different diets i.e., poultry feed, sugar+wheat flour and rusk affected different biological parameters of B. germanica such as, mean incubation period, hatching percent of eggs, nymphal developmental period and adult longevity. B. germanica fed on poultry diet showed maximum hatching (94.65%) followed by sugar+wheat flour (88.54%) and rusk diet (87.04%). Similarly, maximum male and female longevity was recorded on poultry diet (144.4 to 153 days) followed by sugar+wheat flour (122 to 126.6 days) and rusk diet (118.6 to 126.4 days). Whereas, the minimum mean incubation period was recorded on poultry diet (14.62 days) followed by sugar+wheat flour (16.19 days) and rusk diet (17.52 days). The minimum mean nymphal development period was recorded on poultry diet (38.38 days) followed by sugar+wheat flour (39.18 days) and rusk fed cockroaches (43.28 days).