This study has shown that Pontogammarus robustoides has a multivoltine life cycle in central Poland, with three generations per year (spring, summer, and autumn). Reproduction lasts from March/April until October, when the last breeding females are found. The first juveniles appear in May and are present in the population until the end of October. Spring and summer generations mature in a very short time (4–5 weeks). Females born in May and July start breeding at a body length of 8.5 mm, whereas the length of overwintering females breeding in spring ranges 11–18 mm. The number of eggs laid is exponentially correlated with the size of a female (r²= 0.89).