The aim of the study was to determine how the spread of contagious agalactia in sheep and goats in the Odesa region depended on the age of the animals and the season. From January 2016 to December 2018, 1,964 ewes and 1,484 nanny goats of different age groups were studied by ELISA for antibodies to Mycoplasma agalactiae. The highest incidence of contagious agalactia was registered in one-year-old animals and was 59.7‒83.0%, two-year-old ruminants showed 17.0‒40.3% prevalence, in livestock at the age of 3–4 years no serological evidence of the disease was registered and in ewes and nanny goats older than 5–6 years 1.5–3.6% were infected. The most susceptible were young animals at the age of one-month (11.6‒14.5%). The first peak of the disease was recorded in March‒April (21.0‒26.1%), in the lambing period, which coincided with the beginning of lactation and the suckling period, and the second peak occurred in June–July (28.9‒34.2%), the period of maximum lactation and of manual milking of sheep and goats. The results of serological investigations indicate the circulation of M. agalactiae in small ruminants in the south of Ukraine. To avoid greater dissemination of the pathogen, appropriate measures should be applied and strategies for its control need to be drawn up.