Field pea (Pisum arvense L.), also known as Austrian winter pea, is increasingly being planted in Croatia and its surrounding to produce high-quality roughage. The main characteristics of the variety are short vegetation, high forage yields and excellent forage quality that is reflected in the high protein production. Seed production of peas is a very complex process. In agricultural production the yield is under the influence of plant genetic potential and environmental factors, especially of the precipitation amount during the growing season. Seed production of forage pea variety 'Osječki zeleni' along with the climatic conditions for a nine-year period (2004-2012) were analysed. The analyses showed large variability in yields, germination and 1000 grain weight as well as oscillations in the amounts of precipitation during the growing period of winter peas in the analysed years. Pearson's correlation coefficient analysis showed a lack of relation between yield, germination and 1000 grain weight. There was no correlation observed between the tested parameters and the total amount of precipitation during the growing period. Thus it can be concluded that the observed parameters were substantially influenced by other environmental factors.