Stability of protein and oil content of 13 soybean varieties were examined using linear model across seven locations and during six years. Due to heterogeneity of environments all year/locations was distributed in to two groups, based on achieved yield. Stability of protein content differed in the low and high yielding environments, while average values show only minor differences. In contrast, oil content stability was slightly changed in the low and high yielding environments, while the average oil content were significantly higher in the low yielding environments. Environmental factors influenced the correlation between oil and protein content in soybeans. Negative correlation between protein and oil content was observed only in the high yielding environments, while varieties in low yielding environments lack this well known inverse relation.